UBR on an AR-10

Dammit! Now I want my 308 carbine again. [gohome]


Remember this RAY?

You were shooting my 308 in its first configuration? The not so soft to the shoulder TROY stock before my UBR. :)





http://www.youtube.com/watch?v=jOORe...yer_detailpage

Yep. I didn't like the Troy stock. Still don't.

I assumed our friend already knew about the regular 308 carbine buffer. I though he was looking for a heavy buffer solution. Then most you can squeeze out of a normal 308 carbine buffer is about 2.5oz. The slash buffer he mentioned is 5.4oz and helps with extraction and bolt speed issues. So I assumed he was looking for an alternative, heavy buffer for a 308 carbine. In my experience, its either make your own or buy slashes if you want a 308 buffer that's above 5 oz. Sorry for the confusion.

Quote:

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Originally Posted by thvigil11

I assumed our friend already knew about the regular 308 carbine buffer. I though he was looking for a heavy buffer solution. Then most you can squeeze out of a normal 308 carbine buffer is about 2.5oz. The slash buffer he mentioned is 5.4oz and helps with extraction and bolt speed issues. So I assumed he was looking for an alternative, heavy buffer for a 308 carbine. In my experience, its either make your own or buy slashes if you want a 308 buffer that's above 5 oz. Sorry for the confusion.

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When I first read Dustin's post what I got what his problem was, he wanted to put the UBR on his 308 lower and thought he had to do something super special to do it, nothing special about that.

Mine was a factory CMMG 16" upper and a factory CMMG lower other than the cosmetic accessories I switched out I never had a problem or fail with the stock 308 3.8 oz buffer.

We all know though that each custom rifle will always come with quirks and challenges once you get them done so who knows.

It is all good [Beer]

Quote:

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Originally Posted by Skully

When I first read Dustin's post what I got what his problem was, he wanted to put the UBR on his 308 lower and thought he had to do something super special to do it, nothing special about that.

Mine was a factory CMMG 16" upper and a factory CMMG lower other than the cosmetic accessories I switched out I never had a problem or fail with the stock 308 3.8 oz buffer.

We all know though that each custom rifle will always come with quirks and challenges once you get them done so who knows.

It is all good [Beer]

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Yeah no worries here, just the realization that we were talking on different levels. The heavy buffer fix is not so important on the midlengths, especially since CMMG pays attention to other things like proper port sizing and such. Its the carbine length systems in 308 that tend to run way overgassed and meet with extraction problems.

"We all know though that each custom rifle will always come with quirks and challenges once you get them done so who knows."

True words right there. Some times its fun to play with a challenge, other times you end up pulling all your hair out.

[Beer]

If you want to use the Magpul UBR stock on your AR10, go to www.762sass.com. They sell the special short and heavy buffer you need to use to work with the UBR stock. The standard carbine buffer is still a bit too long. The UBR stock uses a special shorty buffer tube. They also sell a slightly shorter buffer spring to go with it. Or just cut the standard spring down a turn or two.
The buffer should be about $50ish. The spring is about $10ish.

http://www.762sass.com/product.php?p...a2902c66f62569

Couple of points to consider. Buffers are pretty basic little parts. It's pretty easy to drive out the role pin, pop off the rubber bumper and fill it full of lead shot. I go a different direction though. As a Heavy Metal multigun competitor, I need recoil as low as possible for those fast courses. For that I need the best brake available (legal for my division) and the rifle needs to be set up tits. Heavy buffers are fine for helping slow down the carrier and deal with the over gassing, but a far better way to go is to switch to adjustable gas and low mass internals. The PRI and the Seekins adjustable gas blocks can be had for around $60 and both are excellent products. You will spend a little more to add the gas block, but it will really help with smoothing out the muzzle jump.

My personal set up is an 18" barrel with mid length gas, adjustable gas block, low mass BCG, JP captured buffer spring system, UBR stock and my own custom brake. My rifle runs very reliable and the muzzle just sort of dances around in the center of the target at 20yds. I can shoot 600yd targets and then jump up and hose paper targets at a dead run, like it was an 223. In 308 it is far better to dial the gas to where it should be, then to compensate for over gas with heavier parts. A PRI gas block, DPMS 308 buffer and spring will set you back $100 total. You can pull one of the weights out of the buffer to get the same reciprocating mass as a low mass bolt carrier. In the end you will have a much better shooting rifle and the UBR stock you wanted.

Again, it's good to see such good advice coming out from our members, its the best part about this site! My piece of advice, IGNORE all the other online forums who say to use the Slash Heavy Buffer, I didn't need to use it as well as others here and I'd NEVER recommend anyone pay $125 for just a buffer!

This is what I mean about tuning your AR10 to run properly. This is my JP 308 rifle with the gas dialed, my own brake design and full power 155gr ammo. Notice that even with low mass internals and the gas dialed in just right, the reciprocating mass still rocks the rifle a little. The lower the mass and operating pressure, the less the rifle will move. 308 is different from 223 in that you can't just drop on a nice brake and make it feel like an airsoft. A good brake will do a lot, but the whole platform needs to be tuned to give best results.


https://www.youtube.com/watch?v=EtT2mRj8FC0