For those of you running SR-15s with the A5 system...

[CQC.45]

I have researched and read every thread pertaining to the topic off of this forum and others and am still seeking some information.

For those who run either the 16" Mod1 and/or the 14.5 SR-15 (I have both uppers), what A5 buffer weight do you run and what is the lowest power ammo you are running successfully? I'm not interested in Russian steel case, but would like to be able to use other .223 including PMC.

I would like to not have to buy the H0, h1, and H2 buffer to experiment with if I don't have to lol. Any information would certainly be appreciated.

[Dmaynor]

Per a thread I found here I switched my 14.5" to the Vltor A5 buffer with a H3. There was some talk of just using a regular Colt spring and a H3 buffer. I can't verify that.

As long as it's good ammo you shouldn't have much trouble. You start getting into the cheaper stuff and it won't generate the kinda pressure you need for a full cycle.

[tom12.7]

I have researched and read every thread pertaining to the topic off of this forum and others and am still seeking some information.

For those who run either the 16" Mod1 and/or the 14.5 SR-15 (I have both uppers), what A5 buffer weight do you run and what is the lowest power ammo you are running successfully? I'm not interested in Russian steel case, but would like to be able to use other .223 including PMC.

I would like to not have to buy the H0, h1, and H2 buffer to experiment with if I don't have to lol. Any information would certainly be appreciated.

Most guys have success with the MOD1 A5H1 combo, with a Colt rifle spring. That is a common setup.
The factory 14.5" SBR can use the the same Colt rifle spring with the standard A5H2 buffer with good success.
The one thing consistent about the .223 bronze PMC is that it's weak and not consistent, so YMMV on that ammo.

[1911-A1]

I have an A5 kit (spring, buffer and extension) on my 16" SR15, and I cycle everything including PMC .223. The PMC feels like a .22, though. It seems to just BARELY cycle. It's VERY soft with an A5 kit. Never tried steel cased stuff, though.

[hjmpanzr]

I ran the A5 on two legacy SR-15 for a couple of years. Currently, I'm running A5 on a KAC 14.5 carbine and KAC CQB 11.5 (KAC 14.5s have replaced all my 16" so I don't have a Mod 1).

The A5H2 (the standard) has worked with absolutely no problems (surefire suppressor and unsuppressed) on legacy SR-15 16", 14.5s and the 11.5 using over a thousand rounds each of .223 77 gr Black Hills Ammo, .223 75 gr Hornady TAP.

I recently ran a couple of boxes of .223 PMC (along with .223 77 gr BHA) through the 14.5 and 11.5 using both A5H2 and A5H3. No problems but with the H3 the brass was ejecting or more accurately "dribbling" out at about 1:30-2:00 unsuppressed on both types of ammo unsuppressed. Adding the suppressor moved ejection back to about 3 o'clock but the brass flew a couple of feet instead of the dribble effect, although it's really easy to collect your brass when that happens.

Reinserting the A5H2 made me more comfortable and both rifles were still very smooth and no problems. Consequently, I keep H2s in them standard.

It has been my experience that you will be just fine with A5H2 (suppressed or not).

I picked up the H4, H1 and H0 for testing purposes but when I've been out I haven't had the time to test it out.

[tom12.7]

The std A5H2 does work in some 16" KAC SR-15s, some seem to be gassed harder than others. Clean and lubed guns in warmer climates have fewer issues than the ones in less than ideal conditions. There's not much of a difference in felt recoil between the A5H1 and A5H2, but there is a big difference in reliability between them for this application. If the rifle is for serious use, I would say to use the A5H1. If it's a fun gun, go ahead and try the A5H2.

[mr h]

Hope you dont mind but I have experience with the a5, just not with kac stuff but my barrels are g.i., fn 20's, colt a2 20's and m4 14.5's. All of which seem to have smaller gas ports than barrels made by different companies with the same length, just based on ejection performance.

I have noticed weak 223 ammo including wolf does not cycle properly in cold weather, below 50ish, with the h2 buffers.

I also had one fn 20" that short stroked with imi m193 brown box and a h2 buffer at a temp of 40 degrees.

Since then I have started using h1 and h0 buffers. Then dont feel all than much different when using federal m193, especially in the longer barrels.

In my colt 14.5 with imi 193 my son was still getting sluggish carrier movement in 40-50 deg weather so I went back to a carbine stock. Partially due to improper shouldering but still. I even opened this gas port up by about .002".

[Ferris2son]

I ran the A5 on two legacy SR-15 for a couple of years. Currently, I'm running A5 on a KAC 14.5 carbine and KAC CQB 11.5 (KAC 14.5s have replaced all my 16" so I don't have a Mod 1).

The A5H2 (the standard) has worked with absolutely no problems (surefire suppressor and unsuppressed) on legacy SR-15 16", 14.5s and the 11.5 using over a thousand rounds each of .223 77 gr Black Hills Ammo, .223 75 gr Hornady TAP.

I recently ran a couple of boxes of .223 PMC (along with .223 77 gr BHA) through the 14.5 and 11.5 using both A5H2 and A5H3. No problems but with the H3 the brass was ejecting or more accurately "dribbling" out at about 1:30-2:00 unsuppressed on both types of ammo unsuppressed. Adding the suppressor moved ejection back to about 3 o'clock but the brass flew a couple of feet instead of the dribble effect, although it's really easy to collect your brass when that happens.

Reinserting the A5H2 made me more comfortable and both rifles were still very smooth and no problems. Consequently, I keep H2s in them standard.

It has been my experience that you will be just fine with A5H2 (suppressed or not).

I picked up the H4, H1 and H0 for testing purposes but when I've been out I haven't had the time to test it out.

Exactly my experience.

[tom12.7]

The regular current 16" KAC SR-15 models when cold and fouled will not consistently cycle fully enough to run properly with the A5H2.
I've done cold weather testing of these in the past, and that was the result.
Tomorrow and Tuesday I'm doing a lot of cold weather testing with temps down to -10F. I can squeeze in some more testing of this combo, but I won't dedicate much time or ammo to it, as I'm confident in my prior results.

[Saginaw79]

A little off subject, but I run an H buffer and my rifle will run fine with PMC, Federal, Rem/UMC. I don't think an overpriced special piece of kit is needed. I run my 14.5 and my 20" with that setup