Only other point I would add is to check hammer strike as well.
On Smith's, with the cylinder open, pull cylinder latch backward and it will allow the piece to be cocked. Place your finger/thumb under firing pin hole and pull trigger. It should "slightly" sting.
Same action on Colt's. Rugers? Don't have a clue how to do it on theirs.
If you don't get that "sting", then you possibly have a weak hammer spring. Maybe not a deal breaker, but it is an aspect I check as well as timing, gap, etc.
Final thought is to look at the top of the topstrap, where the forcing cone protrudes from the frame. Is there "cutting" there? This will appear as a dug out area immediately above the forcing cone. If so, it is a pretty good indication that magnums or hot loads were fired pretty regularly. This is also often present in pre WW2 revolvers, just due to age, and if you are buying for collector value don't let it stop you. For shooters, I check this area as one of the first things I examine.
Hope this helps, but the above post is GREAT information imo.
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