308 buffer ?

[jamesob]

Ok here's the deal, I have a tm 308 lower with a collapsible stock and a pro fab 18" upper. The bolt doesn't go back far enough to catch on the hold open. The buffer spring is 11" 1/4 long with 35 coils. The buffer is 2"1/2 long,the buffer tube is roughly 7" 3/4 long end to end. From what I have read everything is right except the amount of coils the spring has causing it to coil bind. Does this sound correct?

[nate76239]

It sounds like the buffer is correct but the spring isn't. I have a DPMS . 308 rifle buffer and spring, the spring is slightly longer than 12 inches but I counted 37 coils. I linked another thread from a while back and the buffer spring for .308 carbine should have around 27-29 coils. I sold my carbine spring and buffer to the guy who started this post.

http://www.calguns.net/calgunforum/showthread.php?t=1153583&highlight=308+carbine+spring

[jamesob]

5 coils difference is about the amount it would need to lock the bolt back.

[G38xOC]

this happened to me on 1 of my build . they shipped A2 spring instead of carbine . I just cut few coils off and been golden since .

[A-Tak10]

Anyone have experience wit this same issue for a Magpul MOE fixed length stock (MAG404)?

I have a Pro-Fab 308, 20" upper, and the buffer and spring don't let the bolt go back far enough to hit the catch. I put about 40 rounds through the gun, and it functions ok, but I'm guessing I'm doing damage because the buffer is bottoming out. The buffer tube fits perfectly in the stock, no gap or anything (I'm confident that the tube itself is the correct length), so I'm assuming it's the buffer or spring. I bought kit on Amazon, so good possibility something it's right, but there seems to be a lot of variability in this space.

I've read that you don't want to use a carbine buffer with a rifle stock, but I'm not sure what else to do. Buffer spring has 39 coils, is about 12in long. seems like it should work, but doesn't...

Is it possible that the Pro-Fab BCG is longer than most? and requires some special buffer or spring? Maybe just an issue with rifle length stocks? seems like folks are using carbine setup and not having issues...

[nate76239]

How far does it go if you manually charge it back? It's possible the butt stock screw is too long, the Magpul stocks use the shorter A1 stock screw and comes with the screw. Was this a new build or did you switch from an A2 stock and possibly left the longer screw? On second thought I believe there's a 1inch difference between the screw lengths and you probably wouldn't be able to charge the bolt far enough to load a cartridge. I doubt the bolt carrier is too long

[gemini1]

I have a carbine buffer and spring on my 308. Spring is 11 1/4" long and has 29 coils, buffer is 2.5" long.

[A-Tak10]

It was new build, only screw I have is the one that came with the stock. The bolt looks to be about .5in from where it should be. Bolt catch hits the chamfered front of the carrier instead of the bolt face.

Just bought new dpms rifle buffer and spring from midway...will take one variable out of it....

[A-Tak10]

Gemini, I assume your stock is adjustable? With the rifle letgth fixed stock, the buffer tube is longer, and a different spring and buffer (5.25 in long buffer) are used. I've read that if you use a carbine buffer and spring in a rifle length tube, you can break your lower (the lug that the buffer tube screws into gets stressed), but I suspect when mine was bottoming out, I was stressing the lug as well.

[A-Tak10]

New buffer solved the issue. I'm assuming that even though the other one I bought said it was for a 308, it was for a 223. The new one else is about 0.5in shorter, and everything works good now. The brass was ejecting at a bit of an odd angle before, I'm assuming it had something to do with the buffer bottoming out as well.

While the parts were shipping, I disassembled and put some FDE Duracoat on, looks good, and I'm expecting it to shoot good as well!