jbrown, its one of those things that 'either it works ,or NOT, its the NOT that can be dangerous and get one hurt or worse......but that being said, many of try to be of help but cannot "see" through this damn screen......many times you "hear " folks say piece of cake, not a problem and yes, there are times when you will find it just 'drops in" that being the fitting of the cylinder from a " like, vintage" gun, allows this to happen, and being "used" ( fitted" just may about drop in or at least need a bit of "final fitting") BUT, it is incumbant upon us that do KNOW , and realize that "$hit happens" must tell you and remind you that is NOT always that easy or simple and like 'Pandoras box' can open up a can of worms........and in the case of firearms can be not only dangerous, but lethal..........
if any doubt or concern, thats what the factory is there for,and will help you, but many of us do try and "save a dime".....and hopefully you can find a cylinder that is close enough to work....make sure you get your hands on a cylinder that is at least the same size ( overall length) of the cylinder that is in YOUR gun, and WORKS, and use those measurements......if a tad longer, it can be 'adjusted" , made to work, with a bit of stoning or filing...if not do not buy a "pig in a poke" and waste your money on the "too small, too short" ones..............lesson learned, remember ALWAYS, "safety first..."
Good luck
And as noted above, GOOD book and worth every penny.............it'll help.