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run8
12-04-2009, 7:37 PM
I built up an AR in .308 using the CMMG lower and DPMS upper, put a VLTOR butt stock, using the same buffer and buffer spring that came with the stock. I noticed on the Riflegear web site they had the parts to upgrade your buffer and spring for .308 so I bought it. I can see the difference in the parts, to accomodate the increased fire power between .223 and .308.

If I had not changed out the buffer and spring and had used the one that came with the stock, would I have noticed a difference or would the part wear out faster?

Here's the rifle btw.

http://www.railsaroundthebay.net/firearms/IMG_1522.jpg

Frank

kenjimatic
12-04-2009, 8:01 PM
I would like to know also. I got a MK3 with an ACE skeleton stock kit with the AR-15 buffer and spring.

C.G.
12-04-2009, 9:06 PM
AR-10 or .308 variants buffer and spring are not interchangable with AR-15 buffer and spring. I am not sure what the result would be from using AR-15 buffer and spring in a .308 but at the very least it would not function properly.

run8
12-04-2009, 9:12 PM
I can tell the springs are coiled differently and there's more tension on the .308 spring, also the buffer is smaller and seems more dense than the regular one.

AR-10 or .308 variants buffer and spring are not interchangable with AR-15 buffer and spring. I am not sure what the result would be from using AR-15 buffer and spring in a .308 but at the very least it would not function properly.

Hoop
12-04-2009, 9:23 PM
I have heard of people using carbine buffers in place of 308 ones, but since you can buy a .308 buffer from midway for ~25$ I don't think it's worth it to use a 223 one.

xr650r
12-05-2009, 7:39 AM
If you have an 308 style carbine buffer tube (which is slightly longer than an AR15 carbine buffer tube), you'll need an H3 standard length carbine buffer and a 308 recoil spring. If you're running a standard AR15 length buffer tube (with the 308 spring, of course), you'll need a special shorter (and heavier) buffer. I believe they're about $100 (Slash's buffer).

AR10's in carbine and rifle format use the same spring (it's heavier than a standard AR15 carbine or rifle spring)

Info here:
http://www.ar15.com/forums/topic.html?b=3&f=62&t=378850


Armalite now makes their CAR stocks mil spec diameter so you can use AR15 stocks over their buffer extensions, BUT they "might" not collapse/stick out too far since they are 1' longer than a AR15 buffer tube


CAR Extension measurements:

Brand,type/length/diameter

OLD Factory Armalite AR10 extension: 8" External, 7 3/4" internal, commercial diameter 1.171"
NEW '07 Factory Armalite AR10 extension 8" external, 7 3/4"" internal, MIL spec diameter 1.145"
VLTOR AR 15 extension : 7 1/4" external, 7"internal, mil diameter 1.145"
Magpul 93B extension: 7 1/2" external, 7" internal, diameter doesn't matter
AR15 commercial extension: 8" external, 7" internal commercial diameter 1.171"
AR15 commercial extension 7 3/4" external, 7" internal, commercial diameter 1.171"

Basically a custom buffer (like Slash's) will allow you to use a standard AR15 buffer tube w/ a standard AR10 (heavier) spring. A standard AR15 H3 buffer with and AR10 spring in the standard AR15 carbine length buffer tube will NOT allow the longer AR10/DPMS308 style bolt to travel rearward enough to function properly.

http://i42.photobucket.com/albums/e303/taylorwso/carbuffersspingstape.jpg