300 BO and best barrel length/cycle for rifle

[nekshot]

We want to put a 300 BO barrel on a ar for sub use. The rail is 1 and 1/8 ID for 15 inches. I originally thought a 14 inch barrel with pistol gas tube would work good. After reading Lloyds thread on his 300 and others input I realized my approach was short on actual sub barrel operation. I will pin an extension on to the barrel to be legal. What would the recommended barrel length, twist and gas tube length be for sub shooting. I assume the possibility would be there to shoot super sonic if so desired. One good thing is short barrels are cheaper! At this barrel length is the accuracy better between cheap barrel vs short top of the line barrel? Your in put will be thoughtfully ingested and pondered upon!

[Moonie]

We have had 2 16" barrels with carbine gas, they work just fine for subs and supers as long as you choose the correct boolit/powder combination. We now have an SBR with 10.5" using a pistol gas, all we have really shot in it are subs as we use a suppressor with it. I also have a 7.5" encore pistol, just for fun, really fun shooting that one with the suppressor, no worries about gas.

Shorter gas systems can be easier to get to cycle I hear, the only time we had a problem was trying to use W296/H110 with subs, my sons carb gas ran fine, mine wouldn't. Using slower powders fixed that issue.

[popper]

My 18" 1:10 carbine gas works fine with the UMC 220 subs. The 10" 1:8 pistol should do fine too, just never tried. I don't shoot subs much but from reading, 10" with a can is quiet, shorter is NOT. But then you go to SBR or pistol. I went to H2 and AGB on the 10" for supers to avoid overgas.

[osteodoc08]

You could always do a 8-10” “pistol” with pistol length gas system. To me, that’s the perfect sub 300BLK gun once you add a can.

[nekshot]

from all input I believe a 14 1/2 inch barrel with my home made no-flash extension attached and a carbine buffer will do! Good, now that is decided I can move unto more important things, such as the evening meal. Thanks for input fellas you all are a great bunch!

[asmith80]

I have one with a 16" barrel and one with a 10.5". Both with pistol gas tubes. The shorter barrel runs just fine with no issues whatsoever. The longer barrel was cycling way to hard and gas was venting out from under the gas block with the same load. I switched to an adjustable gas block to control the over gassing. I barely had to open up the adjustable port before it started cycling reliably, and much more softly. 16" barrel with a pistol tube and a suppressor would definitely need some way to limit gas

[popper]

Pistol port location was designed for fast powder and slow boolits. Length of the barrel after the port is just as important as before the port. K=PVT we know but replace T with t (time after port) and you see that short barrels reduce pressure to cycle the bolt. Solution is open up port or slower powder.