Educating yourself - on how to check a used revolver - and to evaluate it --- becomes part of the fun of adding revolvers to your collection, in my view.
I have about 25 S&W revolvers in my collection now ... 1 inherited, the rest of them were all purchased used.
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If you can, try and find someone at your local range ...who has a few / talk to them --- what do they own, calibers, why those specific guns../ maybe they will let you put a few rounds thru some of their guns...and you can start to evaluate what you like in terms of grip size, weight, barrel length, caliber, etc.../ even though you have some revolvers, its probably time to take a bigger look at revolvers in general - as you get ready to jump into the deep end (with the rest of us )...because its not just how to check / its evaluating what you really want in revolvers, in my view...
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Personally, .357 Mag is my favorite caliber...and S&W is the gun that fits my hands the best ...and I like their triggers the best...( S&W's like model 19's, 27's, 28's, 66's, 686's ...etc are all models I like in 2 1/2", 4" and 6" barrels ) but you have to figure out what suits you the best !