a parts question

[dammitman]

so awhile back i purchaced a DPMS LR308 from wallyworld as they were blowing out any scary guns and ammo. it seemed to be a good deal but i didnt like the collapsable stock so i replaced it with a magpul MOE rifle stock. of course i had to change the buffer tube, buffer and spring as well. i cannot remember where i got the buffer tube, buffer and spring from and thats the question. do those type parts interchange between ar15 and ar10 (LR308)? and can i use the buffer tube, buffer and spring that i removed from the LR308 on a ar15 build? i think i figued out that the tube is the same but i dont know about the spring and buffer. anyone have any insight?

[jbrew44]

The 308 buffer will be shorter than an Ar-15 buffer to allow for a longer bolt carrier. I think the spring is 308 specific as well.

[dammitman]

that makes sense, i will keep those parts separate and marked as such. thanks!

[devildogandboy]

i asked a similar question about switching the A2 stock between an ar15 and m5(308). answer was i would have to use different spring and buffer.

Bruce

[LRRPF52]

There are 3 main options for the SR25/AR10/LR-308 large frame AR's.

Option 1:
ArmaLite AR10 carbine extension tube (also called an A5 for the AR15). This tube is slightly longer than an AR15 carbine tube, so it allows you to use AR15 carbine-length buffers, but heavier weights are necessary for the LR-308 carbine with CLGS and excessive dwell time (way over gassed).

Option 2:
Rifle length tube common to AR15 and AR10, with AR10/LR-308 rifle buffer (shorter than AR15 rifle buffer, longer than carbine buffers).

Option 3:
AR15 carbine length tube, DPMS LR-308 carbine short buffer. This is the least reliable option, and is the factory one from DPMS.

If you are going to be using a carbine extension, my recommendation is the ArmaLite/A5 intermediate extension tube, with AR15 heavy carbine buffer, at least an H3 or heavy buffer from Heavybuffers.com

Another thing you can do is use the JP Silent Capture Spring for the AR10. They come already at carbine length, and can be augmented with spacers if the extension tube is longer. They have different weight kits on them for the springs and weights as well.

If you went to the MOE Rifle stock, you need a rifle extension tube with an ArmaLite AR10 or DPMS LR-308 rifle buffer and longer AR10 rifle recoil spring. The AR15 rifle buffers and springs are not compatible with AR10's and LR-308's because the AR15 rifle buffer is longer, preventing the BCG from retracting fully into the tube, causing short cycling and failure to strip a new cartridge from the magazine.

This is the most common mistake made in parts assemblers in the LR-308 world.