05-05-2024, 12:35 AM
I don't have a lot of experience ( a little with 556 and 300 blk) in shorter barrels, but would think your best choice would be carbine length. Just 2 cents however.
Look at how much barrel lies beyond the gas block to the muzzle, that's your dwell-time "length". 6Arc pressures being Saami limited to 52 ksi, vice the 556 or 300 Blk at (IIRC) 56 ksi, inch for inch the 6Arc should have a lower pressure than either; and gas volume right between those 2 via the bore size. So I would vote for the carbine length. I personally don't prefer shorter gas tube lengths b/c that means more back pressure to the bolt... and possibly into my face, leakages from the chamber area I mean.
Look at how much barrel lies beyond the gas block to the muzzle, that's your dwell-time "length". 6Arc pressures being Saami limited to 52 ksi, vice the 556 or 300 Blk at (IIRC) 56 ksi, inch for inch the 6Arc should have a lower pressure than either; and gas volume right between those 2 via the bore size. So I would vote for the carbine length. I personally don't prefer shorter gas tube lengths b/c that means more back pressure to the bolt... and possibly into my face, leakages from the chamber area I mean.