First time I made an AR barrel from a blank, I was unsure about the correct diameter of the gas port. Gas port sizes vary with barrel length and barrel diameter. I drilled an undersized hole, and went to the range with a battery operated electric drill and a set of numbered drills. Initially, the action would not open enough to eject and feed. I kept increasing the port diameter step by step until fired cases were reliably ejected, rounds fed, and the action would lock open on an empty magazine.
The Charlton gas system is interesting and a bit different. The piston does not extent all the way to the gas block/gas port. The pistol is relatively short, and there is a tube which brings gas back to the pistol face. I suspect that this affects the dwell time. The M-1 Garandicon system, for example, delivers a sharp impulse to the piston; the Charlton's would be softer.
A Charlton is a lot heavier than a rifle - this would also be a factor in the amount of perceived recoil.