# How to machine the end of a 1.5" dia rod perfectly round?



## toysareforboys (Aug 11, 2019)

I have a solid plastic (Delrin) cylinder, 1.5" dia x 3" long.

I need to make one end of it perfectly round, like the top of this:




I have a mini hobby lathe (BusyBee B-244). How would that be possible?

I can make it pointed, but want to try it round:




Let me know please and thanks!

-Jamie M.


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## 682bear (Aug 11, 2019)

Search for 'ball turner'... plenty of info about it...

-Bear


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## toysareforboys (Aug 11, 2019)

682bear said:


> Search for 'ball turner'... plenty of info about it...
> 
> -Bear


Wow, neat! Never seen such a device!! https://littlemachineshop.com/products/product_view.php?ProductID=2568

Looks great. Should that be the one I get? My lathe is set up for 1/2" shank size stuff so looks like it should work!

-Jamie M.


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## 682bear (Aug 11, 2019)

That should do fine on delrin... may be a little lightweight if you want to use it on steel.

Many of us have made our own ball turners... I tried to download a photo, but for some reason, the website won't let me right now...

-Bear


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## toysareforboys (Aug 11, 2019)

682bear said:


> That should do fine on delrin... may be a little lightweight if you want to use it on steel.


By steel do you mean aluminum? 99% of the stuff I do is aluminum or delrin.

Thanks for the quick replies 

-Jamie M.


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## 682bear (Aug 11, 2019)

That one should be ok on aluminum... you may have to take light cuts to get a decent finish... IDK... I haven't used one like that.

-Bear


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## markba633csi (Aug 12, 2019)

When we say steel we really mean steel, it's not a code word or anything like that LOL
being as how steel is harder to machine than other non-ferrous metals, some light duty machines struggle with it


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## toysareforboys (Aug 12, 2019)

markba633csi said:


> When we say steel we really mean steel, it's not a code word or anything like that LOL


I thought he meant metal 

-Jamie M.


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## Alexander McGilton (Aug 12, 2019)

Does nobody stop to ask what this guy is doing with a 40mm grenade launcher?  The item in the first image is a less lethal round used by military and law enforcement. If you are a member of law enforcement, then it's a really bad idea to use home made projectiles, for in the event that you cause unnecessary harm to an assailant or protester you are taking on liabilities otherwise directed to the manufacturer. Not to mention any policies directed down through the chain of command.    
http://www.defense-technology.com/p...shable-foam-round-1093449.html#sz=12&start=34


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## toysareforboys (Aug 12, 2019)

Alexander McGilton said:


> If you are a member of law enforcement


Not a member, thanks 

I just launch stuff, what else are you supposed to do with it?







-Jamie M.


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## toysareforboys (Aug 12, 2019)

markba633csi said:


> being as how steel is harder to machine than other non-ferrous metals, some light duty machines struggle with it


I haven't tried to machine steel yet, but I'm going to try and machine stainless soon! Good thing my gears are metal 

-Jamie M.


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## markba633csi (Aug 12, 2019)

Interesting hobby, be careful


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## toysareforboys (Aug 12, 2019)

markba633csi said:


> Interesting hobby, be careful


Always am. Unless you're shooting explosive rounds (mostly illegal for civilians in Canada) there isn't too much that can go wrong. One thing to remember is to always make sure your gunpowder is packed tight. Say if there's a gunpowder cup in the 40mm case/hull, if you only fill it up half full, when you go to launch the powder settles to the side of the cup, allowing the primer flame to go across the top of the powder, which ignites it all at once causing a big pressure spike. If you're only filling a cup half full use tape to hold the powder down or pack some wadding on top of it 

I think in Cali you can own 37mm smooth bore launchers without any special permit right?? But 40mm rifled launchers are registered as "Destructive Devices"? In Canada 37mm smooth bore launchers are "non-guns", i.e. you can launch them "anywhere", anyone can own them, no licence required. Colt M203's (40mm rifled) require a CDG (dangerous goods) licence (basically a destructive devices permit, mostly just for the military, very difficult for a civilian to get) but LMT M203-2003's (40mm rifled) are available for civilian sales (I know, makes zero sense) as non-restricted firearms (you just need a PAL/firearms licence). Because the LMT 40mm is a "real gun" you can only launch it where it's legal to discharge firearms (i.e. not within city limits unless at a gun range, but you can at a friends farm out of town, etc.).







-Jamie M.


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## Mitch Alsup (Aug 12, 2019)

toysareforboys said:


> One thing to remember is to always make sure your gunpowder is packed tight.



Black powder does need to be packed tight in order to avoid problems with detonation.
Smokeless "gun" powders do not.


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## Eddyde (Aug 12, 2019)

Mitch Alsup said:


> Black powder does need to be packed tight in order to avoid problems with detonation.
> Smokeless "gun" powders do not.


What about Pyrodex? Asking for a friend...


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## Mitch Alsup (Aug 12, 2019)

Pyrodex conflagrates and sane packing densities--just like smokeless gunpowders.


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## Latinrascalrg1 (Aug 12, 2019)

Mitch Alsup said:


> Black powder does need to be packed tight in order to avoid problems with detonation.
> Smokeless "gun" powders do not.


Regardless if smokeless powders need to be pack tight or not Wouldn't it be Good Practice of making it a habit to pack all gun powders so that there is less chance for making a fatal mistake?

Ive never loaded anything with any kind of gun powder so I Am clueless here but i would be sure to follow proper/safe usage instructions and do my research beforehand regardless.


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## toysareforboys (Aug 12, 2019)

Mitch Alsup said:


> Black powder does need to be packed tight in order to avoid problems with detonation.
> Smokeless "gun" powders do not.


Nice to know smokeless doesn't like to detonate like BP! Using super hot shotgun primers (209A) doesn't help with the BP detonation issue. I've only used Goex Fg (black powder) so far (in my 37mm, that's the one in the fireball pic), makes such a mess of the barrel. For my 40mm I've set up loads using Triple Seven FFg, a little "hotter" but supposed to be easier to clean up than Goex but so far haven't found a place I can launch it so can't testify to that.

I'd like to switch to using smokeless but have zero experience with it (I've been using black powder for all kinds of "projects" for 15 years or more). I made an extra thick/strong hull to help develop smokeless loads:




The 1/2" dia tail of the projectile is a press fit into the hull so should allow somewhat complete combustion of the smokeless. The big pressure spike will be absorbed by the case/hull and the projectile will be moving well by the time the gas is allowed to escape the hull into the barrel so the barrel itself shouldn't see too much pressure (hopefully).

-Jamie M.


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## cjtoombs (Aug 12, 2019)

Poor propellant bed ignition is the culprit behind the pressure spikes.  It's not that the powder settling below the primer is getting "ignited all at once", it's that it isn't.  It's a bit counter intuitive, but I've seen it first hand.  If the ammunition isn't going to be handled much, you can load the propellant charge and then top it off with cream of wheat or corn meal (depending on which you like the smell of better, breakfast or popcorn).  For ammunition that is handled enough that the propellant and filler might mix, you have to use something else. We even had some special cases that were partially filled with epoxy for a certain project in order to tailor the case volume to the load.  And this was all with smokeless powder.


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## Mitch Alsup (Aug 12, 2019)

I reload 45 LC using about 1/2 a case of Trail Boss. 
Trail Boss is a powder that has been designed to occupy a large space (with little weight) and still burn <relatively> slowly.
The typical 8 pound canister only holds 5 pounds.

You might get enough umph out of TB for your project. 
And there is basically no way to have so much that something goes boom.


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## toysareforboys (Aug 12, 2019)

Mitch Alsup said:


> I reload 45 LC using about 1/2 a case of Trail Boss.
> Trail Boss is a powder that has been designed to occupy a large space (with little weight) and still burn <relatively> slowly.
> The typical 8 pound canister only holds 5 pounds.
> 
> ...


Wow, neat powder! Never seen it for sale in Canada but I'll look extra hard. How's the smoke with it?

Thanks!

-Jamie M.


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## cjtoombs (Aug 12, 2019)

Also, if you don't need it for looks, I don't know that at the velocity that those will shoot that the nose of the projectile will make much difference to performance, that truncated cone you did on the lathe may be just fine for your purposes.  They make bullets that are basically that shape for pistol cartridges anyway.


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## 682bear (Aug 13, 2019)

Smokeless powder will detonate... especially with light loads in large cartridges...

Several years ago, I played around with some Trail Boss while experimenting... trying to see how accurate I could get 160 grain cast lead bullets to shoot out of a 30.06... the trail boss didn't prove to be a very accurate powder. 

IIRC, my load book said you could take practically any standard metallic cartridge, fill it full, then weigh the charge, and that would be 'max load' for that cartridge...

-Bear


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## Tozguy (Aug 13, 2019)

Considering that you are cutting Delrin, I would consider using one of these to cut a round nose on a lathe.
https://www.amazon.ca/Kempston-3014...=2025&creative=165953&creativeASIN=B0013KRS1K
It should be straightforward to mount the bit in the tool post on center.


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## Tozguy (Aug 13, 2019)

About the reloading, based on my experience with shotgun and light pistol loads for smokeless powders, I would go to the trouble of packing the case if only to get consistent combustion during your trials. I don't know how well read you are on pistol loads but there is a lot of info in that niche on using smokeless powders with short barrels at low pressures.
Trail Boss would be my first choice to try. 
Do you have a bullet trap?  Using smokeless powders it is often possible to see the bullet fly at low velocities.


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## Cadillac STS (Aug 13, 2019)

With Delrin what about getting it close to round on a sanding wheel or sanding belt then put it in the lathe to finish out with various levels of sand paper (Maybe files) to smooth.  Lathe will keep it concentric.  

Wouldn't need a ball turner on the soft material.


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## cjtoombs (Aug 13, 2019)

682bear said:


> Smokeless powder will detonate... especially with light loads in large cartridges...
> 
> Several years ago, I played around with some Trail Boss while experimenting... trying to see how accurate I could get 160 grain cast lead bullets to shoot out of a 30.06... the trail boss didn't prove to be a very accurate powder.
> 
> ...



To be technical correct, most smokeless powder (except for some propellants tried by the military) will not "detonate". That doesn't mean they won't blow you're gun up, but a detonation, in technical terms, is a very specific thing.  A deflegration explosion is what you see in gun failures, when the gun breech or cylinder explodes in a few large pieces.  This is due simply to the pressure inside increasing slowly (relative to a detonation) until the strength of the containment is exceeded.  A true detonation produces small fragments due to the detonation wave propagating around the cylindrical body and producing rarefaction waves that tear the container apart, these waves bouncing back and forth inside the pieces and tearing them apart in turn, until there is not enough energy to further tear the pieces apart.  I suspect that these low load gun failures are related to the poor propellant bed ignition I discussed above, if they exist.  Discussion of them has been around since the 1950s, P.O. Ackley attempted to replicate them and failed.  I have shot reduced loads and never had a problem.  If it does exist it is only in very specific loads and then under very specific conditions.


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## toysareforboys (Aug 13, 2019)

Tozguy said:


> Considering that you are cutting Delrin, I would consider using one of these to cut a round nose on a lathe.
> https://www.amazon.ca/Kempston-3014...=2025&creative=165953&creativeASIN=B0013KRS1K
> It should be straightforward to mount the bit in the tool post on center.


Ahhhh, neat idea!! I think I'll give that a try, thanks!

I found some Trail Boss powder locally  On the 37mm/40mm forums they said they use up to 20 grains. I'll start with 5 grains and work my way up. Should be fun!

-Jamie M.


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## toysareforboys (Aug 15, 2019)

This Trail Boss powder is weird, you pay for 1LB of it but you only get 9 ounces! lol 







It's absurd how light/less dense it is vs. goex or triple seven. 20 grains just about fills the whole case not leaving much room for a tail on the projectile. If I end up eventually using that much I'll have to increase the diameter of the chamber.

Thanks again guys for all the help, even with the non-machining info. Can't wait to give it a rip.

-Jamie M.

EDIT: I decided to spin up another prototype hull/case with a 7/8" diameter chamber instead of the 1/2" one above. That'll give me 98.5mm³ of chamber volume instead of 32mm³, nice. I'll try and get it finished tomorrow


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## rwm (Aug 15, 2019)

This looks pretty cool. Can you tell me more about the projectiles and intended use? Do you recover the blue projectile? Why round instead of stock? Do you launch other objects in front of it? What other kinds of load does this use. (aside from grenades!)
Robert


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## toysareforboys (Aug 15, 2019)

rwm said:


> This looks pretty cool. Can you tell me more about the projectiles and intended use? Do you recover the blue projectile? Why round instead of stock? Do you launch other objects in front of it? What other kinds of load does this use. (aside from grenades!)
> Robert


The only range close to me is an indoor range (50 yards) and that's the only place I can use my new 40mm launcher (unless I find a friend that lives on a farm out of town). They for sure don't allow explosive or incendiary ammo and don't allow use of projectiles that bounce off the backstop. I tried some real commercial police rubber rounds (called strikers iirc) but they bounced off the backstop all the way back to our feet so those aren't allowed. I would like to test a solid Delrin round and see how much it bounces back. These rounds will be just for range use.

All of my home made rounds I used with my 37mm launcher (which you can launch "anywhere") were using Goex Fg black powder which has way too much smoke and fire to use indoors, so I was going to try Triple Seven or smokeless Trail Boss for the indoor rounds with Delrin projectiles.

At the end of the day when they sweep out the range they put all my projectiles in my locker for me so I can reuse them.

I wanted to try round so it looked more like commercially available rounds, and that it'd probably slide into the launcher slightly easier and possibly have better aerodynamics.

In Canada, having your firearm license allows you to manufacture some explosives (binary like Tannerite), and you can also get your pyrotechnics license and display fireworks class 2 license if you want to cook up even more special rounds. When I asked the local authorities if I could launch such items out of my launcher they said "don't do it" but couldn't give any reasons or laws against it. I looked through all the regulations and the only thing I can see is that the round can't detonate on impact, but time delay (fuse) is fine. I'm sure it'd be super unwise to launch a Tannerite round out of your launcher (even if it didn't blow up in the chamber it'd probably blow up on impact if it hit something before the fuse lit it off, which would make it illegal, even if unintentional). Flash powder would be way more stable and wouldn't detonate on impact, but if it ever lit off in the barrel you could kiss your launcher goodbye (at the minimum).

Other rounds you can shoot are smoke "grenades":












And there are chalk marker rounds, parachute flares (you shoot them straight up), some people shoot golf balls but the ones I tried were a VERY tight fit in the barrel (pretty much had to use a press to force it in), or D batteries 

-Jamie M.


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## rwm (Aug 15, 2019)

Very interesting. I would think the Parachute flares could be a lot of fun. Delrin projectiles could get expensive if not reusable.
Robert


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## toysareforboys (Aug 15, 2019)

rwm said:


> Very interesting. I would think the Parachute flares could be a lot of fun. Delrin projectiles could get expensive if not reusable.
> Robert


I bought the Delrin super cheap from China, it's probably not real Delrin but feels like real Delrin when machining. I looked on alibaba and found a supplier, any colour, any diameter, any length, and the prices were half the price per foot of the local shop. And get this... I thought the crazy price was per foot (which was half of the per foot cost of the local shop), but it was PER METER!!! That makes it one sixth the cost of the local shop  Takes a month to arrive but as long as I plan ahead it's not an issue. I ordered way way too much because I thought it was per foot, so I got triple what I thought I was getting, so I'm well stocked up for now lol.

The machining and mess could get real annoying, so hopefully they will be reusable at least a few times! I'd imagine the tail will get worn out and not seal tight anymore, then I could make a cup with a slightly smaller chamber and re-machine the tail a bit smaller  might work to extend their use.

The project for today is done! Portable 50 ton hydraulic press with adjustable height:
















It should save me a ton of time and effort instead of doing it on my arbor press as I use it to press in primers and the projectile.

If I exceed the strength of the 1/2" threaded bars I can upgrade them to 1" but I only have good drills up to 1/2" and home depot only had two 1" threaded rods in stock and I didn't feel like driving around to a bunch more then buying a nice $$ 1" drill bit (or trying with my china 1" bit).

-Jamie M.


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## toysareforboys (Aug 15, 2019)

OMG! Yes yes YES! The press works sooooo good! Pretty quick to change the height as well! Can't believe I was putting all my weight on my arbor press all this time, and having it give up with the projectile tail half way in usually, then have to resort to the sledge hammer 

It pressed my projectile tail into the case/hull without breaking a sweat, didn't even notice any difference in pumping handle pressure! It was 0.014in oversized (hole was 0.884, tail was 0.898).






After pressing it together I filled it up with Trail Boss smokeless powder (through the primer hole) and it held exactly 7 grains! Nice. I'll start with that as my first load, and if everything goes smooth and I think I need more power I'll either trim the tail a hair shorter to fit more powder or drill out a bit of the center of the tail.

Going to be super sketchy pressing the primer in as the last step!! I'll have to figure out a way to rig up a rope to the pump handle so I can pump it from outside my shed incase it goes boom 

-Jamie M.


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## Tozguy (Aug 16, 2019)

Why not load the conventional way ie. press in primer, add a measure of powder then press in projectile?
It is not usually a problem if the powder gets slightly compressed when seating the bullet.

Whichever method you use to press in primers and bullets, there MUST be a provision for venting pressure away from the operator if there is a BOOM.

Pressing a primer into an empty case allows venting through the case but there must be a vented bushing between the press and the top of the case that directs flow away from the operator. I would continue to use the arbor press for installing primers.

Likewise when pressing in the bullet, there must be a vented bushing between the bottom of the case and the press. The vent must be large enough to pass the primer and direct flow away from the operator.


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## toysareforboys (Aug 16, 2019)

Tozguy said:


> Why not load the conventional way ie. press in primer, add a measure of powder then press in projectile?


If I put the primer (and powder) in then try and press the projectile in the air pressure builds up huge in the chamber and either pops the primer out or prevents me from fully seating the projectile  I'm pressing the projectile in 1 inch, that's compressing the chamber from 0.666cu in to only 0.05cu in! I'm not sure how to calculate what the air pressure inside would be at the end but I assume it must be pretty high. I also know when you're compressing air that much it gets very hot, if I compress it too quickly it might get hot enough to ignite the powder = boom.

If I'm pressing the primer in as the last step I can't figure out a way to use a pressure release bushing. With the press holding both the projectile in as well as the primer, wouldn't the actual case/hull explode?

-Jamie M.


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## RobertB (Aug 16, 2019)

toysareforboys said:


> With the press holding both the projectile in as well as the primer, wouldn't the actual case/hull explode?
> 
> -Jamie M.



Make a jig to hold the case by the rim when pressing in the primer.


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## Tozguy (Aug 16, 2019)

As Robert just mentioned or maybe shorten the stem on the bullet? The compression ratio of .666 to .05 c.i. seems extreme to me.


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## Eddyde (Aug 16, 2019)

toysareforboys said:


> The project for today is done! Portable 50 ton hydraulic press with adjustable height:
> 
> 
> 
> ...


Um, be careful, that ½" rod isn't nearly strong enough to handle 50 tons. The grade 2 hardware/big box store rod is only rated at around 1,100 pounds. Even if you calculate the tensile strength of mild steel at around 50,000 psi, the root diameter of the rod is only about .405 so about 6,400 pounds, still far short short of 100,000 pounds.


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## toysareforboys (Aug 16, 2019)

RobertB said:


> Make a jig to hold the case by the rim when pressing in the primer.


The rim is pretty weak (2mm thick aluminum) but it should be strong enough to just press in the primer. I don't have a milling machine but I think I can build a thick tube that the case will slide into with enough room for the projectile to come out and the back cut out to allow the flame/pressure to go away from me. Thanks for the ideas 



Tozguy said:


> As Robert just mentioned or maybe shorten the stem on the bullet? The compression ratio of .666 to .05 c.i. seems extreme to me.


I'm used to having to keep black powder compressed, with smokeless I guess I can shorten the stem some then use some wadding to keep the powder in front of the primer.



Eddyde said:


> Um, be careful, that ½" rod isn't nearly strong enough to handle 50 tons. The grade 2 hardware/big box store rod is only rated at around 1,100 pounds. Even if you calculate the tensile strength of mild steel at around 50,000 psi, the root diameter of the rod is only about .405 so about 6,400 pounds, still far short short of 100,000 pounds.


Thanks for the great info. Princess Auto (local shop) sells grade 5 and grade 8 threaded rod and nuts but they are renovating or something and had zero in stock  If I used four 1" threaded bars of grade 8 what could that take approximately?

Thanks again everyone, tons of great info 

-Jamie M.


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## John O (Aug 16, 2019)

Check Brafasco and Bolts plus they should have threaded rod. Sometimes even lower prices.


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## toysareforboys (Aug 16, 2019)

John O said:


> Check Brafasco and Bolts plus they should have threaded rod. Sometimes even lower prices.


I talked to Brafasco, the only grade they have above grade 2 is grade b7, which is $110 per 3ft or $440 for 12ft.

Stainless 304 (they didn't know the tensile strength) is $183 per 3ft.

I'll check with Bolts Plus and some other shops 

-Jamie M.


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## toysareforboys (Aug 16, 2019)

Fastenal has B7 - 3ft x 1in is $75 each. Finish: Plain Tensile Strength: 125000 psi Yield Strength: 105000 psi Sku#47683
Bolts plus: B7 , $50 ea.
CCS Industrials: B7, $26 ea., lots in stock.

Made CCS confirm twice it was the right stuff, nice price!! They have a great price on a cobalt 1" drill bit too, will pick that up for enlarging the holes 

-Jamie M.


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## Latinrascalrg1 (Aug 16, 2019)

With the amount of adjustability you have with the current setup along with the expensive cost for the larger harder threaded rod you might be better off all the way around using a different cheaper but stronger material such as some pipe and hardened pins!  I dont know if cost is a factor or not but im guessing pipe material is gonna be much easier to source then that hardened very expensive thread rod!


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## toysareforboys (Aug 16, 2019)

Latinrascalrg1 said:


> im guessing pipe material is gonna be much easier to source then that hardened very expensive thread rod!


I can return all the threaded rods and nuts, etc. that I've already bought, and I don't mind the cost of $26CDN ($19.60USD) per 3ft rod and CCS industrials is just down the street from me and they have lots in stock, so I'll probably go that route.

-Jamie M.


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## Eddyde (Aug 16, 2019)

toysareforboys said:


> The rim is pretty weak (2mm thick aluminum) but it should be strong enough to just press in the primer. I don't have a milling machine but I think I can build a thick tube that the case will slide into with enough room for the projectile to come out and the back cut out to allow the flame/pressure to go away from me. Thanks for the ideas
> 
> 
> I'm used to having to keep black powder compressed, with smokeless I guess I can shorten the stem some then use some wadding to keep the powder in front of the primer.
> ...


1" grade 8 would do it and give a nice safety to margin.


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## Mitch Alsup (Aug 16, 2019)

cjtoombs said:


> To be technical correct, most smokeless powder (except for some propellants tried by the military) will not "detonate". That doesn't mean they won't blow you're gun up, but a detonation, in technical terms, is a very specific thing.  A deflegration explosion is what you see in gun failures, when the gun breech or cylinder explodes in a few large pieces.  This is due simply to the pressure inside increasing slowly (relative to a detonation) until the strength of the containment is exceeded.  A true detonation produces small fragments due to the detonation wave propagating around the cylindrical body and producing rarefaction waves that tear the container apart, these waves bouncing back and forth inside the pieces and tearing them apart in turn, until there is not enough energy to further tear the pieces apart.



Powder is supposed to burn; this means the flame front is moving slower than the speed of sound (in that mixture at that temperature that instant).
This is known as a conflagration.

Detonation is when the flame front is moving faster than the speed of sound--this necessarily produces a shock wave and reaches pressures ordinance metals cannot withstand.

Then there is the secondary pressure spike. This happens if the projectile is pushed faster than the speed of sound, and then, while still inside the barrel, the projectile slows down (friction) and the conflagrating flame front reaches the back side of the projectile and reflects back through the original flame front instantly detonating (conflagrate becomes detonate) the unburnt charge remaining. This usually happens when insufficient powder is placed in the case before loading. This is why there is a lower limit to the amount of powder to put in a case.


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## toysareforboys (Aug 16, 2019)

Eddyde said:


> 1" grade 8 would do it and give a nice safety to margin.


Sweet! I got it all ordered, pick it up on Monday. Thanks again.

-Jamie M.


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## toysareforboys (Aug 16, 2019)

Finished off the final machining tonight of the smokeless 40mm inert prototype ammo 

Second last step is cutting the bevel for the extractor and grip fingers (so when you push the ammo into the chamber/barrel, if you pointed it straight up without closing the barrel it wouldn't slide back out). Last step is cutting the 45 degree bevel on the front of the projectile.







And she's done and done!
















Thanks again everyone for all your help plus safety tips!

-Jamie M.


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## Tozguy (Aug 17, 2019)

Thanks for sharing and the good photography!


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## Cadillac STS (Aug 17, 2019)

toysareforboys said:


> If I put the primer (and powder) in then try and press the projectile in the air pressure builds up huge in the chamber and either pops the primer out or prevents me from fully seating the projectile  I'm pressing the projectile in 1 inch, that's compressing the chamber from 0.666cu in to only 0.05cu in! I'm not sure how to calculate what the air pressure inside would be at the end but I assume it must be pretty high. I also know when you're compressing air that much it gets very hot, if I compress it too quickly it might get hot enough to ignite the powder = boom.
> 
> If I'm pressing the primer in as the last step I can't figure out a way to use a pressure release bushing. With the press holding both the projectile in as well as the primer, wouldn't the actual case/hull explode?
> 
> -Jamie M.



To avoid too much pressure when pressing in the projectile make a very small slot up to about the last 1/4 inch of the projectile so while pressing it most of the way pressure escapes then the last 1/4 inch it seals and puts in a little pressure.

The smallest of slots like scratching of a pin just to let the air out.  Then maybe one on each side in case the pressure release at firing would be uneven.


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## toysareforboys (Aug 17, 2019)

Cadillac STS said:


> To avoid too much pressure when pressing in the projectile make a very small slot up to about the last 1/4 inch of the projectile so while pressing it most of the way pressure escapes then the last 1/4 inch it seals and puts in a little pressure.
> 
> The smallest of slots like scratching of a pin just to let the air out.  Then maybe one on each side in case the pressure release at firing would be uneven.


Nice, that could work!! I thought about making a slot but I wanted to keep 100% of the pressure in the case until the projectile is well on its way (1 inch) down the barrel (to reduce the pressure spike that the barrel/barrel chamber will see). I also figured a slot would reduce the re-usability of the projectile because the hot gas escaping through the slot would erode it quickly.

I still might use your idea though because pressing a primer into the cup while the gunpowder is in there is scary 



Tozguy said:


> Thanks for sharing and the good photography!


Glad you like it  Hopefully I'll have some videos to share shortly too.

-Jamie M.


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## derf (Aug 17, 2019)

Instead of machining all those projectiles, you could make a mold and cast them from polyurethane. Much faster and not to mention less expensive.




__





						Alumilite - Mold Making & Casting Resins
					






					www.alumilite.com


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## toysareforboys (Aug 17, 2019)

derf said:


> Instead of machining all those projectiles, you could make a mold and cast them from polyurethane. Much faster and not to mention less expensive.
> 
> 
> 
> ...


If they turn out to be as not as reusable as I'm thinking, I'll probably go that way, thanks!

-Jamie M.


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## Cadillac STS (Aug 17, 2019)

One thing to consider to make things easier is using your lathe to make a custom holder for the press. 

3.5 inch steel round stock 6 inches long or so. 

Bottom bore out an inch or so that will just fit your jack ram. Top bore out just big enough to insert your cartridge including the projectile so it goes in straight. 

Also gives some blast containment. 

So then you have a stable method to do it, not balancing it with pressure risking it going the wrong way.


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## Tozguy (Aug 18, 2019)

Just to be clear, there should be no attempt to contain the blast as pressure will find its way out somewhere somehow. 
Any holder or chamber that would be pressurized as a result of a mishap should be adequately vented in a safe direction.


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## Cadillac STS (Aug 18, 2019)

Explosives are dangerous.  be Very careful. Especially with a hand held devise. To me not worth the risk.


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## toysareforboys (Aug 18, 2019)

First range trip was a success! Still have all my fingers and both barrels survived without issue (barely). They didn't allow pics or video unfortunately. And boy does smokeless powder really take the fun out of launchers. No smoke? NO FIRE?  lol. Not sure why I was so afraid of smokeless?? With 7 grains of Trail Boss it felt like shooting a .22LR (both noise and recoil), vs. 55 grains of Triple Seven FFg felt and sounded like a 12ga (it probably detonated, see the primer bulge pic below)!

Note to self in case I forget: Mount the M203 sight higher so I can keep the gun against my shoulder easier when aiming/firing.







I shot the 7 grain smokeless one first, out of the 12" barrel. Almost zero dirt/residue in the hull, barrel chamber or barrel, sweet. Landed 4ft low at 50 yards using the M203 sight set to 50. I was unable to extract the case from the barrel so for the next shot I just swapped barrels. The projectile took a funny bounce off the floor/backstop and and hit the 45 degree armoured steel baffle near the ceiling and shattered. I could see the blue scuff on the baffle and used that mark to know where to dig in the backstop to find as many pieces as I could:











Next was the 55 grains of Triple Seven FFg out of the 9" barrel. Almost too much smoke for the range but they said if I limited myself to 1 shot every 5 minutes it would be allowed. Recoil was crazy, felt just like a 12ga slug, my wrist and shoulder hurt pretty good. Lots of noise and fire. Makes quite a mess in the barrel and the hull is dirty inside and out but for sure not as sticky/gummy as Goex black powder and cleaned up easy with soap and hot water then wiped it down with WD40. Projectile landed 6 inches high at 50 yards, pretty much right on target, and landed softly in the backstop, no bounceback. Upon recovering the projectile I noticed the tail was missing. On the shooting table just in front of the barrel were little blue plastic pieces so I'd have to assume that the tail broke off or shattered on launch, not really sure what could have caused that, maybe too much pressure on ignition and it shattered the tail instantly? Maybe the powder wasn't packed tight enough and it detonated? That would explain the nutty recoil and the primer cap being bulged and molded into the shape of the firing pin hole!! I looked and looked, all over the range floor, the backstop, for the tail or peices thereof, nothing. The hull extracted from the barrel without issue. I used my micrometer to measure the barrel diameter and checked it from front to back, no bulging, impressive! I find it pretty amazing that it survived that much overpressure (having a projectile that light helped of course).











Check out that primer bulge 






Before I packed up to head home I figured I'd try and get the smokeless hull to come out of the 12" barrel and boom, it slid out perfectly easy... what the fudge?? My only guess is that it's such a close fit that once the shot goes off and the case gets warm it expands slightly making it impossible to remove, then once it cooled down it came out fine. Just a guess.

All in all a great trip, lots of info/data to go on. I think from this point forward I'll stick to smokeless, even if it's less fun it seems much safer.

-Jamie M.


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## toysareforboys (Aug 18, 2019)

Alright, second version of the smokeless setup.






And finished (I shaved .001 off of most of the hull to hopefully help extraction after firing):






Same aluminium cup, projectile tail shortened from 1" to 0.75", 10 grains of Trail Boss smokeless, and oversized the tail 0.040! Yikes. Made some creaking and groaning noises pressing in but she did it. Hopefully that'll get me more combustion of the smokeless.

Should get to light it off tomorrow (Monday), will try and sneak in a camera.

-Jamie M.


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## toysareforboys (Aug 20, 2019)

The new smokeless setup worked AMAZING!!! Flawless combustion, a TON of power, wow. Not quite as much recoil as the detonation of the triple seven yesterday but close! The lady that was shooting .22LR on the handgun range across the hall (I was on the rifle range) came over to make sure everything was ok, lol. She said it was so loud she almost dropped her gun, she was just getting ready to shoot, and then she had to put it down for a while because she was so shaky. I think the smokeless is working good now 

My first pull of the trigger was just a click, looked like a light primer strike (was pretty off center too, weird). My guess is that because the hull is such a tight fit in the chamber that the spring pin in the barrel that's supposed to keep the hull tight/flat against the receiver face isn't able to do its job, so the hull was sitting a hair off the receiver face so the firing pin had to travel too far to hit it. I solved this on the second try by not seating the round as far into the barrel (I did, but used my knife to pry it back a bit) and closed the barrel very slowly and only until the latch clicked, as to keep the hull tight against the receiver face. Worked fine that time.

To avoid the light primer strikes in the future I can a) make the extraction rim on the hull thicker so the barrel better holds it tight to the receiver face and/or b) not make the round such a tight fit in the chamber/barrel. Option b might be required because once again, after firing the round, I couldn't get the hull out of the barrel until I let it fully cool down 

I think I'll go back to 7 grains or less now that I have good combustion, 10 grains is pretty insane, lol.

Once again the projectile hit the steel baffle on the ceiling, put a big scuff in the front of the projectile but didn't shatter it this time. It's probably reusable but might not fly very straight. Next time I'll have to put a camera down at the backstop to see what's going on down there. If I can get my projectiles to land in the soft backstop they'll be very reusable, not so much when they hit the metal baffles.

I was able to sneak in a camera, sorry for the horrible audio as I was right beside where the main ventilation fans are. Headphones users use caution 

[video]














Check out those impressions from the receiver face, and that dent from the extractor push pin! That must have been some serious recoil 











When I went to clean the barrel I noticed it was full of lots of plastic debris (it was spotless before the shot), could it all have come from just this little chip on the tail? There's no other plastic missing from the projectile other then where it looks it hit the metal baffles?!? Very strange!






Can't wait for my next trip, I'll have a bunch of rounds loaded up including some with perfectly round noses (maybe they'll survive hitting the baffles better)!

-Jamie M.


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## Tozguy (Aug 20, 2019)

Just wondering if the tail would survive better if it was rounded (or maybe boat-tail shaped) like many copper bullets.
The tail is most exposed to heat and pressure so that would make a sharp corner prone to erosion. 
The bottom edge of the body seems to seal quite well and have survived OK.



toysareforboys said:


> b) not make the round such a tight fit in the chamber/barrel.


 
Based on how clean the aluminum is on the outside of the hull I bet that your idea is worth a try.
Cutting a slight taper to the hull might make it easier to extract without promoting blowby.


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## toysareforboys (Aug 20, 2019)

Both great ideas, thanks! I'll try boat-tail shaped on the last 1/4" on the new longer tail, and one that's cupped as well, see how each one does.

I like your idea of the taper too, or at least not ALL of the hull has to seal in the chamber, just make a 0.5" sealing band near the base, might work. It'll be easy to see if I'm getting blowby with smokeless as it'll leave white residue on the black receiver face.

If I get blowby with the small sealing ring I might try an o-ring or two, more difficult to insert but should extract very easy.

Thanks again.

-Jamie M.


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## Cadillac STS (Aug 20, 2019)

What is the compound that is used for tracer bullets?  Might add some of that to be able to view the path of flight.


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## toysareforboys (Aug 20, 2019)

Cadillac STS said:


> What is the compound that is used for tracer bullets?  Might add some of that to be able to view the path of flight.


Tracer rounds are prohibited at the indoor range (due to the rubber backstop I assume) 

My friend has a super nice highspeed camera but he says the lighting in the range is so crappy it can probably only do 240fps or so at 1080p, probably not fast enough to see it.

-Jamie M.


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## toysareforboys (Aug 26, 2019)

Did someone say ROUNDED? Woot 







I made it from the normal projectile I shot it today:

[video]




With the rounded nose it's much much easier to insert into the barrel (to push the hull grip clips out of the way)!

I also reloaded it into the hull I shot today! Everything went back together perfectly, another 12.5 gains of triple seven FFg (by weight).

Won't get to launch until Thursday probably 

-Jamie M.


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## Tozguy (Aug 27, 2019)

Just wondering what approach you used to cut the nose round.

How does the round nose stand up to the impact on the baffles?

Also how did you solve the fired hull extraction problem mentioned earlier?

Thanks for the video, nice work.


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## toysareforboys (Aug 27, 2019)

Tozguy said:


> Just wondering what approach you used to cut the nose round.


I used this 3/4" radius router roundover bit clamped in my normal tool holder with a couple washers underneath to get the height centered: https://www.busybeetools.com/products/r-bit-roundover-2in-x1in-x1-2in-shank.html

I ran my lathe in reverse and cut it "from the back".

The only trick to using it is you have to keep the surface temperature of the Delrin under control otherwise it'll get gummy and grab the bit/rip it out of the chuck. I found that holding an ice cube against it while cutting worked perfectly (you only need one hand to do the cutting anyway).



Tozguy said:


> How does the round nose stand up to the impact on the baffles?


I have not fired the round nose version yet but I should get to on Thursday.

The 45 degree angled backstop is made out of recycled car tires all chopped into tiny pieces so it's fairly fluffy/soft so as long as it lands in the backstop any projectile should receive zero damage. The problem is if it bounces off the backstop and hits the armour plate on the ceiling (baffles). I believe if the velocity is too high it bounces off the backstop.



Tozguy said:


> Also how did you solve the fired hull extraction problem mentioned earlier?


I have two barrels, the hull got stuck in my spare 12" barrel, the one in the video in my last post is the 9" barrel that came with my launcher.

I have not extracted it yet. I've made a jig out of delrin to hold the barrel in my 50 ton press so I can press out the stuck hull (the jig has space for the hull to push out the bottom), should be pretty effortless. 

The reason I have not extracted it yet is because I don't want to see the disappointment of the inside of the barrel being damaged. Barrels are next to impossible to get in Canada (they are a controlled part usually, for some reason LMT barrels can get here but not Colt) and are $$$. In my mind, if I haven't seen the damage yet, it isn't damaged. When I wipe away the tears I'll get it pressed out. Not sure I'll have pics or video of that, don't need to be reminded.



Tozguy said:


> Thanks for the video, nice work.


Thanks! Glad you like the video. My range prohibits phones/cameras and video and pictures so it's tricky to record them 

-Jamie M.


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## Tozguy (Aug 27, 2019)

Ice cube...I would never have thought of that!


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## toysareforboys (Aug 27, 2019)

I figured the only part of the projectile that would wear out when re-used a lot is probably the rifling engagement band so I will try out replacing it with a high temperature o-ring instead (specs of o-ring shown in photos for testing are ID: 26mm, OD: 36mm, Cord Diameter: 5mm). Very cheap (26 cents US or 34 cents CAD each shipped), user replaceable if it wears out and should provide a nice projectile to barrel seal and give good grip to the rifling.











I didn't round off the nose of the o-ring projectile because I already know the flight path of that one and I want to see what changes with the o-ring.

It's pretty stiff to get it into the chamber (especially with no lube) and then push the round all the way in (o-ring drags heavy on the chamber). If that gets too annoying I have an idea where I can use t-bolt hose clamps to compress the o-ring and squeeze it inside the hull!! Then it'll be super easy to push the round into the chamber/barrel and as soon as it fires and the projectile moves forward a quarter of an inch the o-ring will expand to engage the rifling. That's how I think it'll work anyway. Once the rest of my order of the hulls arrive I'll set up a bunch of different setups and test them all.

-Jamie M.


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## Tozguy (Aug 28, 2019)

Is the o ring groove square? Seems to me that lube would help the o ring slide into the chamber.


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## toysareforboys (Aug 28, 2019)

Tozguy said:


> Is the o ring groove square? Seems to me that lube would help the o ring slide into the chamber.


Yep, square and a little oversized to allow it to compress lots. What makes it extra hard to slide in is the extractor cut at the bottom of the barrel/chamber. The o-ring likes to try to squeeze out into this cutout as you're sliding it in, and it can get pinched.

To make the barrel easier to clean I spray it down with WD40 before launching, so there will be plenty of lube around to help.

Looks like I've got to work my day off so won't be any launching until next week probably 

-Jamie M.


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## toysareforboys (Sep 2, 2019)

Oh damn, looks like I got some work ahead of me! 












Lathe don't fail me now!

-Jamie M.


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## toysareforboys (Sep 4, 2019)

I made a stainless steel .38 to 209 adapter but man, stainless steel is hard to machine on my little hobby lathe  I think I'll stick to aluminum or the .38 brass blanks to 209's.

The projectile you see without the rifling engagement band and no external o-ring actually has two o-ring's inside!











The one on the right has the two internal o-rings. Can't wait to test that one! I wonder if the o-rings can be reused? lol.






And the one in the center has my stainless steel .38 to 209 adapter:






-Jamie M.


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## Cadillac STS (Sep 5, 2019)

Definitely need to make enough of those to fill an over the shoulder bandolier ammo belt.  Looks like you have one to work with already


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## toysareforboys (Sep 5, 2019)

Cadillac STS said:


> Definitely need to make enough of those to fill an over the shoulder bandolier ammo belt.  Looks like you have one to work with already


haha, yep! That's both a belt and shoulder bandolier. There's a big gun show this weekend. I'll probably wear it as a belt so it doesn't cover up much of the logo on my shirt 






I'll get back to mass production tonight!

-Jamie M.


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## Jimsehr (Sep 6, 2019)

Google          Super simple ball turner


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## toysareforboys (Sep 6, 2019)

Cadillac STS said:


> Definitely need to make enough of those to fill an over the shoulder bandolier ammo belt.  Looks like you have one to work with already


Found out there is a "no ammo" policy at the gun show this weekend so lost my motivation to make a bunch more, lol. 






I should get to cook those off on Sunday if everything goes to plan.

-Jamie M.


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## Cadillac STS (Sep 15, 2019)

Consider making a bullet puller that fits those. So if there is a misfire (cap looks hit but not fired and you have a loaded round that needs to be dealt with) you are ready to easily pull the projectile off and reload it.


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