Shortest AR barrel for successful suppression

[prairiefire]

What would be the shortest barrel that one can use as a reliable suppressor host in 5.56. 10+?? 11+?? 14.5"??
I have read about blowback in the shortest barrels and am not anxious to play that game - but I have no experience with SBR'd ARs...

 

[Docsherm]

What would be the shortest barrel that one can use as a reliable suppressor host. 10+?? 11+?? 14.5"??
I have read about blowback in the shortest barrels and am not anxious to play that game - but I have no experience with SBR'd ARs...

Are you talkimg 5.56?

 

[prairiefire]

Sorry - yes, 5.56

 

[Shoots 700's]

I run a 12.5 both ways it runs perfectly, blow back always happens

 

[alamo5000]

I have a 10.5 that has been suppressed since day one. It runs great.

There are a lot of factors in play here though... In short your question is not specific enough I don't think.

That said I think 10.5 is about as short as I would ever go.

Ammo is another factor as well. The ability to run is one thing but effective terminal performance is another.

Shorter barrels do accelerate the wear on suppressors too.

Depending on the ammo my 10.5 is good within 100 yards for terminal performance. Just shooting it to get a bang it's on the money but velocity is compromised a lot.

 

[nn8734]

10.3” is as short as I’ve run (mk18m1 w/a surefire mini 5.56 can and adj gas block). Shoot it suppressed 100% of the time. No issues with 55g, 62g or 77g ammo (my hand loads).

 

[Clayman]

What would be the shortest barrel that one can use as a reliable suppressor host in 5.56. 10+?? 11+?? 14.5"??
I have read about blowback in the shortest barrels and am not anxious to play that game - but I have no experience with SBR'd ARs...

If you have shortish dwell length and a low back pressure can you won't have an issue on really short barrels.

I've seen 5.5" barrels suppressed with a sandman k and oss 5.56. Both functioned fine without excessive blowback.

5.5" 5.56 is stupid imo but that's a different topic.

10.3-10.5" barrels are routinely suppressed. My 10.5" noveske is suppressed 100% of the time.

Your ability to tune your host and the suppressor itself will be very important for having a smooth, properly gassed system.

 

[clcustom1911]

10.3” is as short as I’ve run (mk18m1 w/a surefire mini 5.56 can and adj gas block). Shoot it suppressed 100% of the time. No issues with 55g, 62g or 77g ammo (my hand loads).

YUP. 10.3 with my full size RC2 5.56, 0.076" gas port, Superlative Arms click adjustable gas block, standard BCG, buffer spring, H2 buffer is rather nice to shoot with all my 55gr to 77gr factory 223 amd 5.56 ammo as well as my assprted hand loads.

M855 while suppressed ejects out at between 2-3 o'clock.

In the Mk18 mod 1's we have at work, unsuppressed, we do standard 0.070" gas ports and H2's. They eject m855 brass between 3-4 o'clock in the Iraq summer and non-summer "winter".

 

[nn8734]

YUP. 10.3 with my full size RC2 5.56, 0.076" gas port, Superlative Arms click adjustable gas block, standard BCG, buffer spring, H2 buffer is rather nice to shoot with all my 55gr to 77gr factory 223 amd 5.56 ammo as well as my assprted hand loads.

M855 while suppressed ejects out at between 2-3 o'clock.

In the Mk18 mod 1's we have at work, unsuppressed, we do standard 0.070" gas ports and H2's.

Yep, your mk18 is set up very similar to mine. I run the standard H2 in my two carbines (10.3, 14.5”). They (and my Mk12 Mod 1) take the exact same load as well (77g smk, 25g of AA2520, LC case, R7.5 srp). That load does very well across all of them.

 

[clcustom1911]

Yep, your mk18 is set up very similar to mine. I run the standard H2 in my two carbines (10.3, 14.5”). They (and my Mk12 Mod 1) take the exact same load as well (77g smk, 25g of AA2520, LC case, R7.5 srp). That load does very well across all of them.

Yup 25 of 2520 and 77's is quite the magical ticket

 

[clcustom1911]

What would be the shortest barrel that one can use as a reliable suppressor host in 5.56. 10+?? 11+?? 14.5"??
I have read about blowback in the shortest barrels and am not anxious to play that game - but I have no experience with SBR'd ARs...

If you're left handed, prepare to get gasses in your face, it's going to happen. Also, source a PRI M84 "gasbuster" charging handle or other charging handle for suppressed weapons which redirect the gasses in a different direction.

 

[ut755ln]

What would be the shortest barrel that one can use as a reliable suppressor host in 5.56. 10+?? 11+?? 14.5"??
I have read about blowback in the shortest barrels and am not anxious to play that game - but I have no experience with SBR'd ARs...

I am going to give you a terrible answer, can't be helped. You can suppress any length AR barrel. The issue that you mentioned (and others) is that it forces more gas back in a DI system and makes the gun unpleasant to shoot. You can spend money changing our your buffer, your bcg, adding an adjustable gas block but at the end of the day a DI AR is designed to push gas back so it is always there. I currently own one AR that is DI and it is a DD Mk 18. All of my other ARs are piston rifles, my current favorite is the Primary Weapon System long stroke piston rifle. The piston guns with adjustable gas blocks let you suppress anything and are easily tuned, no more gas in the face, no more over gassing (unless you want it). Effectively you end up with the modularity and adaptability of an AR with the reliability of an AK. I have shot and messed with the POF, the LWRC, the HK, a couple of Sigs and they all work great. I don't have personal experience with but I have heard that the Adams Arms and the Stag Arms piston systems work really well also.

 

[Clayman]

I am going to give you a terrible answer, can't be helped. You can suppress any length AR barrel. The issue that you mentioned (and others) is that it forces more gas back in a DI system and makes the gun unpleasant to shoot. You can spend money changing our your buffer, your bcg, adding an adjustable gas block but at the end of the day a DI AR is designed to push gas back so it is always there. I currently own one AR that is DI and it is a DD Mk 18. All of my other ARs are piston rifles, my current favorite is the Primary Weapon System long stroke piston rifle. The piston guns with adjustable gas blocks let you suppress anything and are easily tuned, no more gas in the face, no more over gassing (unless you want it). Effectively you end up with the modularity and adaptability of an AR with the reliability of an AK. I have shot and messed with the POF, the LWRC, the HK, a couple of Sigs and they all work great. I don't have personal experience with but I have heard that the Adams Arms and the Stag Arms piston systems work really well also.

The vast majority of gas blow back from shooting suppressed is coming down the barrel, not the gas tube. It doesn't matter if you are using piston or di. You need to tune your host. Delay unlocking and you will have less gas in the face. The MK18 is overgassed. Most combat guns are to insure reliability in adverse conditions.

Plenty of piston guns are very gassy. HK is one of them. Watch the garand thumb video on the new hk even with a "suppressed" setting. Thing is overgassed. Again most combat guns are intentionally overgassed and make for a underwhelming suppressor host.

 

[vinniedelpino]

11.5-12.5 5.56
8-9 blk.

Can you go shorter? Yes, but what do you gain and lose?

 

[W54/XM-388]

This is where one of the OSS suppressors would be a big help in taming the gasses.

Another thing is if you custom load your ammo for the barrel length, so that you try to make sure most of the burn is done when the bullet gets out of the barrel.
As far as length goes, 5.56 works because of velocity, so you are going to want to be at least long enough to get a decent velocity going.
I'd think something in the 10.5 range would be good as a minimum, then if you want to go back to 8, perhaps swap to .300BLK Supers.