XH buffer in 5.56 pistol

[rvanno]

So, I’m new to AR pistols. I recently purchased a Geissele 11.5 inch super duty upper in 5.56. I have an unused LMT defender lower with a sba3 pistol brace, but was short a buffer. Anyway, I ended up finding a XH heavy buffer laying around the garage.

I went ahead and just decided to give it a try, half expecting it to be a single shot when shooting unsuppressed. Much to my surprise, it functioned very well with 5.56 ammo (I did not try any 223). The bolt locked back on multiple magazines and I had no failures.

I plan on replacing the muzzle device and placing an AAC M4-2000 on the pistol this weekend. The pistol will be shot the majority of the time in this configuration. I’m expecting it to function well suppressed. Again, I’m new to pistols. Should I expect a problem with this set up? Should I be looking out for anything when using this heavy of a buffer?

Thanks

[rvanno]

Well, okay. I guess I’ll just figure it out and post back the results.

[Clint]

If the upper will cycle an 8.5 oz buffer unsuppressed, the gas port must be fairly generous.

The M4-2000 is known to have pretty high back pressure.

The combination of the two should be pretty exciting.

[rvanno]

Thanks Clint. Looks like I might be buying one of your gas tubes.

[rvanno]

300 rounds of PMC x-tac 55gr 5.56 today. All suppressed. The gas to the face was moderate (I have certainly experienced worse). I believe I will leave the XH buffer in place. Lower power 223 ammo only cycled well suppressed, as I expected.

[MistWolf]

Oof! An 8.5 oz buffer is heavy for 5.56 AR of any barrel length. That's a higher unsprung to sprung mass than normal and during cycling, pushes the weapon around more. This complicates recoil management.

I think you'll be happier with your new shorty once you get the gas under control and run it with an H2.

[rvanno]

Your probably right. I’ll end up getting a H2 and maybe even a H3 and see how it goes.

[MistWolf]

Your probably right. I’ll end up getting a H2 and maybe even a H3 and see how it goes.

After my experiences, I put forth that if you need or want an H3, get an A5 RE assembly and an A5H2 buffer.

[rvanno]

After my experiences, I put forth that if you need or want an H3, get an A5 RE assembly and an A5H2 buffer.

Got it. I appreciate the help.