Any problems with doing this?
Thanks
None that I’m aware of. Seen it done a few times.
The Canucks do it. It’s called the C7A2.
Any idea on buffer type?
I’m pretty certain they use a CAR (2.9oz) buffer. Anything heavier would likely cause the rifle short cycle when it got dirty or dry or with weak ammo (weaker than 5.56mm NATO). I’m sure KevinB knows for sure.
Hello: I was told to use an H3 Buffer when using a Sliding Stock on 20" rifles.
I haven’t installed the sliding stock on my A2 yet, but, I totally trust the person that advised using the H3 Buffer when I do.
Take Care.
Who told you this Bob?
H3 was essentially designed for rifles with HUGE gas ports or suppressed guns. At 5.6oz’s is way too heavy for an AR with a rifle length gas system.
CAR is 2.9oz
H is 3.8oz
H2 is 4.57oz
H3 is 5.6oz (same weight as a 9mm buffer)
X is 8oz
I guess the question would be what is the weight of the A2 buffer?:eek:
5.2oz for a rifle buffer. BUT the springs are different. TOTALLY different equation. The reciprocating weight is different as well.
The buffer spring? Is it that much different?
Of all the guys that I’ve read about with this set up, I can’t recall any cycling/buffer issues. I always thought that the Rifle length system was much more forgiving compared to the carbine. 
Hello gotm4:
It was a well respected local fellow thats heavily into the M16/AR-15 platform. I’ll ask him again to be sure thow if I do in fact change the stock.
The rifle buffer does weigh 5.1oz correct? If so, then the H3 Buffer @ 5.6oz should work.
Heavier than CAR weight buffers are intended for ARs with CAR length gas systems to slow them down to make extraction easier. Rifle length ARs don’t have this problem. As I said in my last post it’s a different equation.
I set my A4 up with a carbine lower yesterday and shot it a bunch. Standard CAR buffer. I had no issues with it at all, and my A4 was filthy and pretty dry. Recoil was slightly different, but no worse.
I love the looks of my A4, but after years of shooting NTCH from a CAR stock, the A2 stock feels way too long. I’m 5’10", 190#.
Canada uses the H2 buffer in the guns.
Reason why was some who are issued several different uppers need a system that accepts drop on’s without other changes - the H2 buffer was found to be the most reliable from barrels 10" to 20"
They ran testing on 30 guns of ea. 10", 14.5, 16" and 20" thru 2 5k NATO standard reliability testing protocals - the H2 was the best performer.
I only put about 100rds thru a C7A2 - but it worked fine - and my C8SFW upper just dropped on no problems - same with the C8CQB upper.
I run an SP-1 CAR lower with my 20" HBAR upper with no problems:
