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+--- Thread: A R Perfomance (/showthread.php?tid=6683)
A R Perfomance - woohoo - 11-12-2013
Tedward Wrote:So the AA brass is the same as the Lapua and thicker than Hornady and does Hornady have the chamfered base??? What does that do to the function?? Seems like the Chamfer would be easier to get into the bolt.Right, a chamfer will push the extractor to the side easier. AA brass is made by Lapua as far as I know. The Lapua brass flipping out of the bolt can bind because the rim thickness at an angle is wider than the groove in the extractor. It's more of a problem with machined extractors with sharp corners. The problem is worse when someone installs a O ring or D ring under the extractor. The Hornady brass does have a chamfer and will come out from under the groove easier.
ETA- The odd thing is loaded Hornady ammo has the chamfer, I have seen brass with and without the chamfer
A R Perfomance - LRRPF52 - 11-12-2013
I noticed that Hornady brass has a chamfer at the radius of the case head. I think this is meant to articulate with sharp ejectors as well, during the feeding cycle when the cartridge hands off from the feed lips into the bolt face.
This is why I radius or chamfer the ejector face, which deals with the Lapua brass, and is a common practice among hi-power shooters that shoot not only PPC based cartridges, but others as well.
Another funny thing about Stoner design bolt carrier groups is that I saw a picture recently of an original AR10 BCG from the early 1960's manufacture. The ejector was beatifuly radiused around its entire face, and the whole unit was chromed.
As to 7.62x39 bolts and AR15's: There is NO industry standard for the 7.62x39 AR. The original company that did the work on it, and produced a 7.62x39 AR15 as the 7.62 Sporter II, was Colt. Most of the manufacturers who jumped on it in the parts industry like M1S and DPMS used parts that are well known for failure. Much of this was exacerbated with the use of Eastern bloc 7.62x39 ammunition that is really .311" diameter, in US-made .308 bored barrels, spiking the start pressure and bolt thrust, cracking lugs left and right.
![[Image: all.jpg]](http://www.c3junkie.com/m16/762/all.jpg)
The AR Performance 7.62x39 bolt did a lot to address this issue, by using better alloy, correct heat treatment, and melonited barrels.
A R Perfomance - woohoo - 11-12-2013
Right, any larger bolt face than a 5.56 exposes the ejector and makes the case more likely to hang upon it. I have to radius the ejectors on most of the wildcats.
No manufacturer is going to waste their time making a radius on the ejector these days. Armalite was a different company when Stoner was around...literally.
A R Perfomance - LRRPF52 - 11-12-2013
Yeah, for those of us who have been around this industry long enough to remember, we know that Eagle Arms bought the Armalite name and re-branded. My first AR10 actually had Eagle Arms on it, and they still market their economy brand guns under Eagle Arms.
A R Perfomance - Russell D - 11-13-2013
Woohoo, if you are in need of barrels PM me.
A R Perfomance - SG4247 - 11-18-2013
Sorry to keep this thread rolling, this newbie still has questions.
I was so impressed their first Grendel bolt I bought from AR Performance, I ordered a spare. They fit an Armalite barrel extension perfectly...like a glove. Very nice bolt design, and super manufacturing quality.
My AR Performance super bolts measure a .130" face depth. So, I chambered two custom barrels using bolts from AR Performance. Both are head spaced for the AR performance bolt +.001". Then I bought two more .264 Grendel barrels less bolts.
I have 400 rounds on the first ARP bolt and it looks perfect. Rifle functions perfectly with both Hornaday and Lapua brass.
Now compared to a Sota 7.62 or a standard 5.56 we know they both measure .125" bolt face depth.
The 7.62 x 39 bolts I have here, are no way near as good dimensionally as the AR Performance piece. I cannot speak to materials or heat treating, but it is very discouraging to hear that they will no longer be available from AR Performance.
Two questions:
1. Woohoo, where do I get an exact replacement extractor?
2. Woohoo, will anyone's bolt headspace correctly to my barrels that were made using your bolts?
You say the 7.62 x 39 will work in a pinch, well if it does, I dont see it working for very long....
A R Perfomance - woohoo - 11-18-2013
SG4247 Wrote:Sorry to keep this thread rolling, this newbie still has questions.Armalite has stopped making 7.62x39 extractors, take a look at RGUNS.
I was so impressed their first Grendel bolt I bought from AR Performance, I ordered a spare. They fit an Armalite barrel extension perfectly...like a glove. Very nice bolt design, and super manufacturing quality.
My AR Performance super bolts measure a .130" face depth. So, I chambered two custom barrels using bolts from AR Performance. Both are head spaced for the AR performance bolt +.001". Then I bought two more .264 Grendel barrels less bolts.
I have 400 rounds on the first ARP bolt and it looks perfect. Rifle functions perfectly with both Hornaday and Lapua brass.
Now compared to a Sota 7.62 or a standard 5.56 we know they both measure .125" bolt face depth.
The 7.62 x 39 bolts I have here, are no way near as good dimensionally as the AR Performance piece. I cannot speak to materials or heat treating, but it is very discouraging to hear that they will no longer be available from AR Performance.
Two questions:
1. Woohoo, where do I get an exact replacement extractor?
2. Woohoo, will anyone's bolt headspace correctly to my barrels that were made using your bolts?
You say the 7.62 x 39 will work in a pinch, well if it does, I dont see it working for very long....
The difference between the back of the lug and the face of the bolt is the critical dimension, compare those. It seems many extensions being used now are shallow, front to face of lugs. They should be .907". If the depth is shallow and the shank on the barrels are normal length then a normal bolt with a .278"+ lug length will not fit between the 2.
That is why the recess is only .130", the front of the bolt was machined slightly shorter. I can always make more if one breaks, it's just that we are not going to produce them to sell.