This should cycle fine a Carbine length or rifle length is ideal, (would be smoother, and softer recoiling) but a pistol length system will function with supersonic 300 blackout.
If you do run into issues (which you shouldn't) you could always switch out to a stiffer buffer spring.
Advanced armament company even sells a 300 black out barrel with a pistol length gas block included.
midwestgunworks.com/page/mgwi/prod/BAR09105

There's a potential for for the pistol to be overgassed which would be noticeable by gas exiting the charging handle, gas exiting the magazine, brass being thrown forward instead of to the right/slightly over the shooter's shoulder, or a combination of all three. Difficult to tell in advance if this would be an issue due to all the potential variables in play. Solutions would be a heavier buffer weight, stronger spring, or an adjustable gas block.