I was just reading some stuff online and carbine length gas system barrels can be found and typically work fine for .300blk but can have issues under 16in. The 16in barrels I've used are all pistol length gas systems. These 16in barrels are Wilson, BA, and Faxon and maybe one or two more different brands.
Experience the precision of Wilson Combat's Recon Tactical stainless barrel. This 16" barrel is designed for the 300 Blackout, offering a dependable and optimized alternative for suppressed fire with hefty bullet subsonic ammunition.
wilsoncombat.com