80% Lowers

[MattM]

Maybe, but yarn is a lot lighter and portable than metal. Like The Wife says, "I can take my hobby with me wherever we go, yours would require an eighteen wheeler and three phase". True that.

 

[Keith Foor]

Like I said I'm an amateur amateur machinist so I will attempt the 80 then, if successful proceed to the zero.

Every time I throw a ruined piece in the scrap bin I say, "Well I learned something and I can make something smaller out of it". The Wife is an advanced spinner and knitter. She often, after many hours of knitting, will unravel the work and start over and start over if it is not exactly to Her liking. She says that is necessary to get it right. Damn I wish I could that with metal.

Technically you can. A mig welder and an annealing oven would be required, but it can happen. Loose track of which end a critical measurement is referenced off of and the metal gets machined away in the wrong spot. If it's all the way through, back it with a piece of copper and fill it in. This can be a bit difficult on plastics, but metals (other than really hard stuff) can be welded surfaced and made to disappear. The magic of the MIG.

 

[Karl_T]

Like I said I'm an amateur amateur machinist so I will attempt the 80 then, if successful proceed to the zero.

Every time I throw a ruined piece in the scrap bin I say, "Well I learned something and I can make something smaller out of it". The Wife is an advanced spinner and knitter. She often, after many hours of knitting, will unravel the work and start over and start over if it is not exactly to Her liking. She says that is necessary to get it right. Damn I wish I could that with metal.

First off, tell your better half you're making chips. a good part is just a by product

Are you making or buying a fixture to hold the part? that's the key to doing this job right.

Karl

 

[n3480h]

Thanks Keith Foor, for the excellent post above. This is information that is critical to safety for anyone milling an AR lower. As such, I would definitely support making that post a sticky.

Tom

 

[MattM]

Yes, I bought the jig along with the 80.

Chips and swarf sometimes end up in our living room carpet because I track them in. The wife complains but I point out that sometimes we find her pins and needles in the carpet. So we agree to always wear shoes or slippers and advise our guests to do the same. No problem.

 

[planeflyer21]

Something else I forgot to mention. There is a half truth out there that dry firing a firearm will somehow damage it. With RIMFIRE cartridges like the 22 family and the newer 17 family of small caliber rimfire ammo, this is true. The firing pin actually contacts the edge of the barrel and can damage it, the firing pin of both. SO if you are building a rimfire AR don't get crazy dry firing it.

Center fire cartridges do not have the same issue. Because the primer is in the middle of the cartridge the firing ping design is different. The pin can't hit anything with the tip. and most center fire firearms have a well retained firing pin that has a large surface to strike when dry fired to spread the impact out and not land it all on the tip of the firing pin.

Neither paragraph is 100% accurate.

With regards to rimfires it is mostly true. For those manufacturers that put a little bit of effort into quality, they make their .22s with a rebated firing pin: the firing pin is long enough to crush the rim of the cartridge but not long enough to contact the edge of the chamber without a cartridge present. Marlin has been doing this on their rimfires since the 1890s. Ruger installs them on their current MKIII pistols.

As with rimfires, not all centerfires are created equal. Without the cartridge and primer present to absorb the shock of the hammer or striker falling, it can transfer this force elsewhere creating stresses.

One gunsmith who is a Ruger guru, is very adamant about not dryfiring any firearm, regardless of what the manufacturer says is okay.

 

[P T Schram]

Jigs are for those who do not have lay-out skills

I've found the jig to be more of a hindrance than of benefit.

 

[cjtoombs]

You cannot under any circumstances legaly sell a firearm that you make, unless you have the proper FFL to do so. You can give the firearm to children or parents, no one else. When you die, you can will the firearm to someone and after that sales are fair game. I spent a fair bit of time recently looking all this up. Also, depending on what state you live in, there can be other restrictions. I live in California, so while I can build a firearm, it must meet California laws. That means magzine restrictions and handguns are completely off limits, as CA has a list of approved handguns and whatever homede think you can think of isn't on it.

 

[MattM]

Jigs are for those who do not have lay-out skills

I've found the jig to be more of a hindrance than of benefit.

Jigs are for me who has minimal layout skills.

 

[Daddy Dave]

Keith gives us all some very good advice. In that these receivers are very unforgiving to errors. I've done several of these now, and used two different jigs; one from CNC Gun Smithing and one from KE Arms. Both are very fine tools. All drill guide holes are spot-on to mil-specs. I liked the KE better, it has the drill guide holes on both sides, and has hardened bushings on the guide holes. I know some folks don't like them. I'm not sure why. They completely surround your receiver, keep your work square on your table and make set-up a lot easier. After 40 yrs. and eyes not as great, easy is good!! As I've mentioned before drill your holes undersize and finish them off with a reamer, all drill bitts not being equal. Most bitts are for general hole drilling, fine for woodworking, but not for precision gun smithing.