You pays your $ and takes your chance!
Consider a used S&W or Ruger.
Make sure the gun is empty.
Thumbcock the hammer.
Make sure the Cylinder will not rotate, it should lock when the hammer is cocked.
Look inside the back of the cylinder at the top, hold the trigger back and let the hammer down slowly as you contnue to hold the trigger to the rear, you should see the firing pin through the gap at the top chamber.
Thumbcock it again, let the hammer down again slowly but this time release the trigger before the hammer comes down. You should NOT see the firing pin extrude. This means that the transfer bar or hammer block ARE properly installed.
If the Firing Pin does extrude that gun is NOT SAFE TO CARRY WITH AROUND UNDER THE HAMMER! It will fire if dropped on the hammer.
Finally, make certain that the gun cycles correctly when operated double action by dry firing the gun and watching the cylinder rotate.
Remember to make sure that the cylinder locks in alignment with the forcing cone / barrel at the end of each cycle.
Used guns are like used cars, maybe you are getting a deal or maybe you are buying someone's old headache.
If I were in your shoes, I'd save up and buy either a GP-100 or S&W 686, New In Box!:image035: