Is there a valid reason to use a heavy buffer with an adjustable gas block.

[Arizona_Mike]

Confine the discussion to closed-bolt, semi-auto AR pattern guns.

I have been using an H2 with a pistol gas 10.5" 300BLK (because of the high pressures at the pistol port location) and a 20" rifle gas .223 Wylde because the Canadian military uses the H2 (and the US used the H2 or the new H6) for rifle uppers on carbine lowers (longer impulse than carbine?).

Heavier buffers and bolts are supposed to reduce recoil but I wonder if that only makes sense given a "fixed" gas port.

Recently I built a pistol gun using the Adams Arms lightweight bolt which is much lighter than a standard bolt let alone the M16 bolts I use in my DI guns. The bolt is lighter by an amount that swamps any buffer differences and AA claims this reduces recoil. Not only is the rifle noticeably lighter to tote, I have never felt an AR with so light recoil.

So this makes me wonder . . . If I have an adjustable gas block anyway and bolt bounce is not an issue for semi-auto, am I gaining anything using an H2 buffer rather than just using a C with a smaller gas adjustment setting (assuming a Syrac gas block with approximately 16 positions between fully opened and closed)?

In addition to the piston experience, I need to have my gas block out a full 3 turns (12 or 16 detents) on the rifle length upper with the H2 buffer which is more than any other configuration I have tested. That got me thinking, why don't I just use the C buffer and save a little weight and have a cleaner gun?

Does anyone really understand buffer theory when you can also adjust the gas port?

Mike

 

[Arizona_Mike]

This guy says go light: http://www.alloutdoor.com/2013/12/17/adjustable-ar-gas-blocks/

Mike

 

[gotigers]

I have the gas block pictured in the linked article above on two ARs.

One is a 10.5" SBR with a Specwar 5.56 can and an H2 buffer. I wanted to slow the cycle time down and reduce bolt bounce, so I use the H2 buffer. The adj gas block lets me adjust to cycle every thing from weakest Tula to the hottest .mil loads. I started with a non adj gas block and H buffer. After trying several combos, the current combo works the best.

For 3 gun, I built the lightest AR I could for two reasons: light weight and fast follow up shots. Part of the the build is a JP low mass carrier, Tubbs flat wire buffer spring and 2.3oz buffer lets me cycle very fast with almost no recoil. This gun is faster and more accurate than I can shoot. The Syrac adjustable gas block helps use just enough gas to cycle. Too much gas and it would cycle so fast it would wear the receiver out. The Tubbs spring helps prevent bolt bounce.

Unless you're shooting 3 gun or steel rifle matches, I would use a milspec weight carrier and buffer. I cant think of a reason for light buffer system outside of competition.

 

[Arizona_Mike]

Actually I am thinking of just going with a C instead of the standard H2 for my rifle length upper and my 300 BLK upper.

My rifle upper will lock back 80-90% of the time on the 10th position and I run on the 12th.

The 300BLK locks back on the 7th setting for supersonic and the 9th setting for subsonic. I have been running at 9 with no fails. If I wanted to hunt with subsonics, I'd; probably go to 11.

I suspect I can lower that some more with the C.

Mike

 

[Arizona_Mike]

I just wanted to give a long term >2 year followup.

I've been running all my adjustable gas ARs with empty buffers (C buffers with all the internal moving parts removed). The gas is adjusted just enough to reliably activate the LRHO. I have had zero problems. These include a 14.5" Mid 5.56mm, a 20" Mid .223 Wylde, and an 18" .308 Mid+1". I have a lot of shots down-range with no problems. I have not shot the aforementioned pistol length 300 BLK enough to be 100% confident but have encountered no problems so far.

Mike

 

[C-grunt]

Heavier buffers slow the cycling of the action. It also gives more mass for the return cycle to help load the new cartridge into the chamber. There really isn't any downside to running heavier buffers as long as the rifle is reliable.