Also, clean under the extractor and the cylinder under the extractor. It only takes one flake of unburned powder to create a tight opening and closing cylinder. If you can pull the cylinder to the rear to open it, it sounds like there is too much endshake, which will create a binding of the cylinder turning.
I do not shoot .357 magnums after I have shot or cleaned after shooting .38 lead bullets through a .357 chamber, even if they can be chambered. Just me, probably as I do not think a few would hurt the gun.

__________________
Richard Gillespie
FBINA 102