What Buffer Are You Using In Your AR15 300 Blk PDW?

incorrigible

incorrigible

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I have a AR15 with a 7.5" barrel in 300 Blk. Currently is running an H2 buffer that was used for a 7.5" 5.56 barrel and I'm finding its short stroking. I ordered an Adjustable Gas Block to as I want to be able to cycle between supersonic and subs... no positive effect.

So now its time to swap out the buffer, spring or both. So any suggestions... H, H1... or maybe even a 9mm carbine buffer?
 
Last edited:
cr5 said:
Regular carbine buffer and spring, don't need an adjustable gas block either.
What ammo are you running?
Click to expand...

Currently its the H2 buffer and spring pack that was running the 5.56 upper. I need to go lighter... just looking for some input on how light by whats working for others.

Supersonic - 19.5 gr H110 with 168 gr VMax
Subsonic - 10.9 Accurate 1680 with 215 gr Lead FP

As a final kick my ultimate wish list would to be able to open up the Syrac adjustable gas block and swapping uppers to run the 5.56 upper interchangably by adjusting the gas block only. Probably not realistic but I'll put it out there.
 
Juster said:
Did you drill the gas port? I drilled most of the way through and finished with an endmill in the drill press. Then the Adjustable Gas Block.
Click to expand...

So just to clarify, is this suggesting reaming out the existing gas port hole at the same size to make sure its unobstructed, or is it to slightly increase the size of the gas port hole to allow for greater flow volume?
 
incorrigible said:
So just to clarify, is this suggesting reaming out the existing gas port hole at the same size to make sure its unobstructed, or is it to slightly increase the size of the gas port hole to allow for greater flow volume?
Click to expand...
To increase the size of the gas port hole to allow for greater flow volume, reducing short stroking. An adjustable gas port can only reduce gas flow.
 
incorrigible said:
Currently its the H2 buffer and spring pack that was running the 5.56 upper. I need to go lighter... just looking for some input on how light by whats working for others.

Supersonic - 19.5 gr H110 with 168 gr VMax
Subsonic - 10.9 Accurate 1680 with 215 gr Lead FP

As a final kick my ultimate wish list would to be able to open up the Syrac adjustable gas block and swapping uppers to run the 5.56 upper interchangably by adjusting the gas block only. Probably not realistic but I'll put it out there.
Click to expand...

Your ultimate wish list is very possible, That's what the 300BLK was designed to do. You don't need a heavy buffer to run your 223 upper.
My non restricted ACR 300BLK conversion and my 12 inch AR build will both cycle supersonic 110gr V-max with H110 and subsonic 208gr BTHP pushed with A1680 and everything in between with the right powder selection.
Use a standard carbine buffer and spring and a pistol length gas system and after that you may need to tweak your loads a little but you should be able to get it to cycle. I use Lil'Gun for my supersonic loads in the 150-160gr range but A1680 will also work just don't go any lighter than that with it.
Since A1680 is hard to find and I have lots of Lil-Gun I save my A1680 for my subsonic loads.

Good luck.
 
cr5 said:
Your ultimate wish list is very possible, That's what the 300BLK was designed to do. You don't need a heavy buffer to run your 223 upper.
My non restricted ACR 300BLK conversion and my 12 inch AR build will both cycle supersonic 110gr V-max with H110 and subsonic 208gr BTHP pushed with A1680 and everything in between with the right powder selection.
Use a standard carbine buffer and spring and a pistol length gas system and after that you may need to tweak your loads a little but you should be able to get it to cycle. I use Lil'Gun for my supersonic loads in the 150-160gr range but A1680 will also work just don't go any lighter than that with it.
Since A1680 is hard to find and I have lots of Lil-Gun I save my A1680 for my subsonic loads.

Good luck.
Click to expand...

Shiny... thanks!
 
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