I own two S&W Model 27 revolvers. One 3 1/2 and one 4". I just bought the 4" model and have troubles with the cylinder sticking on one chamber. This 4" model 27 was built in 1980, so it has the recessed cylinder. When the cylinder is closed, everything works as it should. But when open the cylinder I have problems. I can open the cylinder as smooth as silk on all but one chamber. On this one chamber, the cylinder hesistates when I try to open it. I can't figure out why. I didn't notice it when I first bought it. I only noticed after my gunsmith install a new ejector pin. (The original pin was missing.) Could this be the cause? I'm at a loss.