How short is too short???

[sgms18]

I shoot nothin but subs, whats the shortest barrel I could go with and still have an accurate reliabley cycling weapon?

[BWE Firearms]

If the bullet sticks out the front of the barrel when a round is chambered your barrel is definately to short.

I have not done much formal testing on this but I wouldn't go much shorter then 10-12" if you want good accurracy.

[Spook]

Originally Posted by BWE Firearms

If the bullet sticks out the front of the barrel when a round is chambered your barrel is definately to short.

Thats pretty funny!

sgms18, I sent you a pm.

JF...?

[LouBoyd]

According to Quickload a 5 inch barrel is sufficient to push a 220 grain Matchking up t0 1050 fps with 44,000 psi loads. A suitable powder would be something like VV-N110 (11grains) or IMR 4227) 12 grains) to achieve 1050 fps. I'm not saying that would be practical in a AR-15. These loads have more energy than more common subsonic loads. They are less efficient with more muzzle blast. Muzzle pressure would be like like a supersonic carbine using modern cartridge, around 15,000 psi. Id want to use a suppressor made for a supersonic 308. The pressure would be as high but it's still a lot less propellant gas.

I chose 10.5" for my 300 Whipser pistols. That's the position where bore pressure and barrel friction become about equal giving minimum energy loads to achieve 1050 fps. I'd expect though that a 7.5" barrel could be made to work OK without much difficulty. . I haven't tried a barrel shorter than 10.5" Part of my decision was that I could shorten the barrel if I didn't like it, but I couldn't lengthen it.

A longer barrel will likely have greater velocity dispersion as bore friction not uniform from shot to shot, at least more variable than the energy from carefully weighed propellant.

A shorter barrel will have higher muzzle pressure and require more propellant, making a more difficult task for the suppressor. For a compact suppressed rifle consider the design by the company called "Refex Suppressors" made in Finland. The main expansion chamber is behind the muzzle and surrounds the barrel back to the receiver. They only extend a few inches beyond the muzzle.

[JFettig]

Originally Posted by Spook

Thats pretty funny!

sgms18, I sent you a pm.

JF...?

I'm still trying to find time to cut my 7" barrel down to 6, then 5". I found a new hobby and its cutting into this one :)
I've got 2 7" barrels out there(mine and another) that are running great.
I do have a blank left, enough to make a 7.5"

Jon

[Spook]

Originally Posted by JFettig

I'm still trying to find time to cut my 7" barrel down to 6, then 5". I found a new hobby and its cutting into this one :)
I've got 2 7" barrels out there(mine and another) that are running great.
I do have a blank left, enough to make a 7.5"

Jon

Hows the accuracy?

[Hoser]

I would rather have a rock solid 10 inch barrel than a 6-7 inch barrel that takes a lot of TLC to get and keep running.

[JFettig]

Originally Posted by Spook

Hows the accuracy?

Honestly I haven't heard too much, both guys I built barrels for are running them on pistols, the one I just finished so he's only had it out once or twice to work up loads - he's running supers only.

The other one I know hasn't been to the range much, I've shot under 2" with my 7" pistol with a bipod, its pretty difficult to get a good rest with AR pistols.

I don't make it to the range much, I wish I could get some more shooting in. Hopefully one of these weekends I can build this other barrel.

Jon

[Expatriot]

Shortest barrel I have seen run reliably is 9.0". I run a 10" barrel on my own Whisper and it works GREAT.