Shortest reliable barrel length for suppressed .300BLK AR?

Crazy Carl

are ya freakin' kidding me?
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I've currently got a 10.5" .300BLK AR15 SBR. Just ordered a Sandman-K & will be going to a shorter barrel to keep the length down. Gun will be used 99% subsonic & I have an adjustable gas block.

Will a 7.5" or 8" barrel function reliably, given those parameters? If so, 1:7 or 1:8? Never dealt with suppressed subsonic .300BLK, so not sure what I'm in for, regarding bullet weights & whatnot. Gun will be used for thick woods deer hunting, range toy & zombie apocalypse duty.

Any tips/advice/experience would be greatly appreciated.
 
If money were no object you could get a Sig 6.75" Virtus upper for your AR lower. But that's like $1300 or so.

You can buy the 7" AR barrel from Q.

Check out liveqordie.com



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Barrel length isn’t the only factor; gas system, gas port, buffer, and ammo are all important and need to be included in the decision

Unlike 5.56, I don’t know what an ideal 300BLK port size is for the respective gas system lengths and what buffer weight should be used.

I’d recommend an adjustable gas block regardless. Superlative is a favorite of mine
 
Barrel length isn’t the only factor; gas system, gas port, buffer, and ammo are all important and need to be included in the decision

Unlike 5.56, I don’t know what an ideal 300BLK port size is for the respective gas system lengths and what buffer weight should be used.

I’d recommend an adjustable gas block regardless. Superlative is a favorite of mine

I would also recommend an adjustable gas system, especially one that has an off position, so you can use it as a bolt gun, which will always be quieter than a semi auto
 
I would also recommend an adjustable gas system, especially one that has an off position, so you can use it as a bolt gun, which will always be quieter than a semi auto

Would i be hijacking to ask for a little more info on how the adjustible gas system works and how the bolt is then locked?
 
Would i be hijacking to ask for a little more info on how the adjustible gas system works and how the bolt is then locked?
If you turn the gas off before it can come down the gas tube, it’s not going to cycle the BCG. That turns your AR into a single shot rifle that happens to be pretty quiet. :cool:

I’ve never actually turned any of mine off, but that’s how they function. Mine are turned down enough they won’t work without the silencer attached.
 
I've got one of those DSG Arms 'Black Friday' uppers, 10.5", pistol gas, adjustable gas block & a regular ol' carbine buffer that I'm changing up a tad. I've never touched the gas block & it runs reliably with supers. Reckon I'll have to find the 'sweet spot' once I switch over to suppressed subs.

Sounds like the consensus is a 1:7 8" & I can live with that. With an 8" barrel & the Sandman-K, effective barrel length will only be 13.4". IMO, that's not too shabby.
 
So the recoil alone doesnt move the bolt? I'm an AR infant. By that I mean i know what the gas system does but the recoil is still tecoil.
What do you think causes the AR-15 to cycle? ;)



Without gas moving the carrier, the bolt doesn’t unlock. You’ll get blast/rise from the muzzle, but the internals aren’t going to function with the gas off.
 
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Q uses a 1:5 twist, as do some of the Sig barrels I believe. They claim it's needed to fully stabilize long and heavy subs in very short barrels like 7' or shorter.

Kevin Brittingham feels 7" is the sweet spot, which is why he designed the Honey Badger around that barrel length.

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I built mine with an 8" barrel and SLR adjustable gas block. I haven't shot it yet, but my goal is to choke it down to barely run 220s suppressed and hope that is also how it is quietest.
 
Q uses a 1:5 twist, as do some of the Sig barrels I believe. They claim it's needed to fully stabilize long and heavy subs in very short barrels like 7' or shorter.

Kevin Brittingham feels 7" is the sweet spot, which is why he designed the Honey Badger around that barrel length.

Sent from my Pixel 2 using Tapatalk

You mean why he copied a rifle to make the Honey badger lol

I digress
 
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