Sounds kinda like the handis binding or a hair long, that or if you have to put a bushing on the cyl. pin you have the wrong cylinder ... is it a Uberti? If so they made two cylinders one had a longer cylinder collar at the chamber end.
I got one can measure mine if you need it, overall or depth of collar...it may be binding with 3 shots of residue. .004" to .006" gap is great cyl. to forcing cone. Usually if the cyl has some play at the halfcock, it will be tight at fullcock...