yes, if the cylinder can "drop in", the front end ( boss/stud/gas ring) should be riding on the inside surface of the cylinder frame;it should be about touching, little or no gap.....the cylinder 'face' ( front) should be clear of the rear of the barrel ( breach) and there should be a "gap" of approx. .004-.008", NOT rubbing, nor touching in this area........of course the "rear" ( ratchets) should be riding against the inside of the recoil shield, a small gap...this gap in front as well as the rear, is your "end play"...we've seen them touching, seen them "gapped"...not sure off the top of my head what the "end play" specs are, but, the cylinder should turn, freely, no rubbing, and very little "play", front to back...if the wrong vintage cylinder, the barrel will be against the cylinder face or vice versa, a large gap on the 'gas ring'...when forward, the cylinder will rub touch or lock up against the rear of the barrel...wrong....BUT as said above, can be "shimmed" and corrected, made to work ...bottom line , it most likely will NOT just "drop in and work....." must be "fitted", then checked for alignment , (timing & lockup...) on ALL 6 chambers...........
and yes, at times they WILL just "drop in and work",but Uncle Murphy was an 'optimist'. :roll: