Hello all,,, Im new to the site and building, but not to M16A2s. I handled in the Corp.  I have a WW-15 AR 15, I want a solid black stock. So I purchased a UTG 308/A2 stock (lets not go into my major malfunctions :o) I want to make sure I use the right  buffer and spring.for my 16 inch carbine barrel. Do I use the new buffer and old (collapsible stock) spring? Also I put the butt stock on and there was a rattling in the back. I think it was the STOCK SPACER?? How do I fix this? . It was before buffer and spring were put in, it rattled.  


I eventually want a 20 inch setup but, wife said bills come first..

now I know you have a carbine, but if you use an A2 style fixed stock, I think you use a "rifle" buffer and spring, and while the 308 A2 stock and buffer receiver tube are the same, the AR15 spring and buffer will be different, based on the AR15 platform, so these should work, you can get these just about everywhere

spring: http://www.midwayusa.com/product/191371/dpms-buffer-spring-ar-15-rifle

buffer: http://www.midwayusa.com/product/910805/dpms-buffer-ar-15-rifle

the links are to Midway but JoeBoboutfitters / Primary Arms / Brownells all carry these parts and should be what you need if I am not mistaken

So the buffer and spring that came with the UTG 308/A2 solid  black stock are too strong and or big for the 16 inch AR-15? The buffer I have from the UTG pack is 5.25'', same as the midway DPMS Buffer AR-15 Rifle model. AND why the rattle?  ty by the way

im not sure what buffer comes with the UTG308 stock kit, so I cant say for sure if its the same or not.  as for the rattle, a lot of guys post that the screw that retains the stock has dried threadlocker on it, and is very hard to screw in all the way, maybe its not completely tight and the spacer is rattling or maybe there is something in the storage space in the buttstock?

Iv read that the spring that comes with the UTG 308/A2 kit is  heavier for a 308 rifle. I dont know if this is true or if it will work. So im going to try the old spring from the 6 position stock with the new buffer and stock setup. As for the rattle I put a real small piece of cloth hockey tape on the end of the buffer tube, around  the edge where you tighten it with the wrench, so its under the cap. Your right, its the extension cap that is making the noise. There is no thread lock on the screw whatsoever. But I will be putting some on once I know the buffer and spring will work.. I tighten the butt screw all the way and apparently the cap is still floating inside. So Im guessing it bottoms out against the lower receiver before the tube is tight.

take a look at this thread, I know you said your buffer measures the same as a ar15 rifle buffer, but these guys indicate there's a difference, so who knows. when I built my AR308 [SunDevil receiver set] I bought a Magpul PRS for a 308 and it came with everything and so far its all I have tried.

thread with more info: https://forum.308ar.com/topic/597-buffer-tube-buffer-and-buffer-spring/