Tiyo, there is alot to unpack so I will just focus on the revolver . I'm going to assume general appearance is to your liking . I will start at one end and go back from there. Not necessarily in order of importance ,but so forget something. Barrel rifling is important, inspecting the lans and groves by visual or bore scope. Looking for clean and well defined. Also take notice of the crown condition. Moving back to the forcing cone. Look for deposits around the cone possible signs of shaving . Look at contact points for damage or discoloration . note that this can be easily cleaned so without a deep look it could look ok. Look at the extractor rod or extractor plunger(single action) for straightness and smooth operation. Now to the most important the cylinder . Should not move with the hammer at rest or at full cock. With the hammer in both positions try to rotate the in both directions , it should not move. If it does it should be a show stopper. Should turn freely at half cock. With the hammer at rest check the cylinder gap between the cylinder and the forcing cone. Feeler gauges are best, but you need to research the proper gap for that model before hand. Loading gate or cylinder release should function smoothly without binding. Trigger pull should be checked in both single and double action, as applicable. You can check firing pin by the use of a dummy round with blue painters tape over the primer to check for impacts. Sights and grips are visually checked for condition, if adjustable, check for smooth operation. If dovetailed check for overall alinement and the have clean lines, not staked. There are always more, if you get the opportunity to test fire do it, but that is a rarity . Good luck, hope this helped.