AR's

[clearcaseman]

correction. the chamber pressures are NOT different. they can be different based on loading. and the facts are you can go either way. this whole 556/223 argument is so silly it stemmed from one time barrels got mixed up in a government order of guns and the report that followed is what started this all. it is all about the max pressure and you are not going to reach blow out pressure unless you are an idiot. 556 NATO is a slightly larger chamber to allow for so many different manufacturers making ammo and the fact that people will be in the field and those just are not sanitary conditions for guns and the gun just isn't gonna be as clean as your gun at the range. 556 NATO is just built to looser tolerances other than that they are the same. go to Walmart and buy 2 different boxes of cheap ammo or go buy a box of Winchester 223 and 556 and measure the case they are the same thing. manufacturers only make one round they do not make 556 and 223 separately . I wish people would get off this kick. in over 20 years of gunsmithing I have NEVER once heard of a mishap related to using the wrong round. now I have heard of barrel obstructions but never for using 556/223 backwards.

Two comments to this post in order to provide accurate information:

1: You can shoot .223 in the 5.56 chamber, NOT 5.56 in a 223 (the dimensions are minutely different
and the chamber pressures are significantly higher in the 5.56)

2: The "denial block" in the casting / machining will not be the deciding factor on an NFA weapon,
it is the drilled hole for the auto-sear and / or any auto parts installed in the lower.

If you have further questions, feel free to ask, I will be glad to answer or provide contact info for those that can answer the question.

 

[george wilson]

Please remember to not get too steamed up in this discussion,guys.

 

[Rick Leslie]

Sharky, looks like you were right on the denial block. I had a factory lower come through the shop last week that had no such block. Also, I looked at a JR (Just Right) AR lower and if I remember correctly, it had no block as well.

All these years of machining around that aggravating little block!!! :angry:

I have also heard (and practiced) the 'no 5.56 in the .223 chamber' business. I have no proof either way, but I like to err on the side of caution.

FWIW: the argument is the opposite on the .308/7.62 NATO side. From what I understand, there are minute differences in the chamber specs for each (NATO vs. SAAMI) and there is a remote possibility that a shell on the lage end of the tolerance will make it into a chamber on the small end of the tolerance and Blamo.

 

[SEK_22Hornet]

I just bit on a polymer lower from EP lowers ( http://www.eparmory.com/default.asp ) On these, the area that need to be removed are "marked" with a different color plastic. Supposed to have the pin locations marked as well - no jig required for completion. I've seen a video where a guy did one with Dremel tool. I have two different mills, so I plan to use a mill and go slowly. These usually go for $100 each but they sometimes have "blem" receivers that they sell for $35 plus $10 shipping. The blems sell out fast, but I managed to catch them when they had a few. This will be a winter project for me, but I'll be happy to share some photos when I get it and when i get started on it. By the way, the one I was able to get is "Zombie" (neon lime) green. I passed on the pink blems. I bought this just for fun and educational purposes, so I'm in no hurry to finish it.

 

[Rick Leslie]

There's a good bit of activity concerning the EP blems going on here: http://www.weaponsguild.com/forum/index.php?topic=44082.0

I have to admit I did buy the Zombie green for me and pink for my wife. But the pink is more magenta. (No, I didn't figure it out, a friend's wife did.)

The take down pin holes are off by about .040" on the blems. The buffer tower is tight on the top and has a slight gap at the radius, but that can easily be fixed. They look like a really inexpensive way to build an AR.

 

[SEK_22Hornet]

Thanks for the link - I'll check it out later. I just got my Zombie Green Blem tonight - it looks pretty good, so I was wondering what the problem with it might be. I'll see how the holes line up with my spare upper. I was really prety impressed with the overall look of the molding - I'll have to see how long I can hold out before digging in. I'll need to find out the correct hole dimensions for the fire control group as a minimum, since it came with absolutely no information. I'll see if I ca dig up a set of drawings somewhere for reference.

 

[Old Iron]

I finished my AR 15 7.62X39 a few days ago, I ordered the upper from Model 1 Sales. I got the 20" barrel with the A2 hand guard and site it is a flat top with removable handle.

It is a great shooter very accurate I.m using the Stoner mags and haven't had any feed trouble yet.

Paul

 

[SEK_22Hornet]

A year or two ago Sportsman's Guide had 7.62 x 39 heavy profile barrels for $70. They are from a US military contractor called ESS Solutions. These were not chrome lined - just parkerized chrome moly. I bought 2 and put two uppers together - one for myself and one for a friend. I have not sat down and put one on paper - just some plinking so far, but they seem to shoot great. Lots of fun! Found a lower parts kit on sale Black Friday from Palmetto State Armory so now I have all the pieces to put my EP Armory poly lower together. So far, I have $45 in the lower, $37 in the parts kit, and $31 in the butt stock and recoil buffer assembly. Just need a couple nice days on a weekend where I can get out to he shop to mill out the lower - 17 degrees in an unheated shop isn't fun...

 

[pineyfolks]

Doesn't the 5.56 chamber have a longer throat than the 223 and by shooting the higher pressure 5.56 in the shorter throat of the 223 causes pressure to rise greatly? I'm asking because I see people shooting 80 to 90gr bullets being single shot that are seated very long. I've been thinking of using a lower to build a 6 x 47. Has anyone used one of these? http://www.midwayusa.com/product/776862/les-baer-custom-barrel-extension-ar-15-steel-in-the-white if so any opinions?

 

[Old Iron]

I did a lot of research on that subject but I'm not getting into it here I did once and I lost my temper so I stayed away for a while. I wrote a long post to the guy but decided to dump it instead of getting things fired up.

Paul