This is my old Ruger Blackhawk three-screw Flat Top .357 Magnum. It is built on the original Ruger MR frame, same as the new flat top Blackhawks and Vaqueros.
I bought it in 1958, which means I will soon have had it fifty five years. By my log book, it stands at just
over 17,000 rounds fired through it. Mostly 158 gr. and 173 gr. bullets backed by stout doses of #2400 powder.
I think that should answer your question.