What knowledge, if any, is gained by knowing what the round count of a gun is? Would you be able to tell approximately how many rounds have been fired by examining the gun? Has anyone seen a gun that has been "worn out" by excessive firing? Inquiring minds want to know.
Mechanical parts wear out as a result of friction. In this case, some examples of wear from high round counts include diminished barrel rifling, assorted spring weakening (in a semi-automatic) and hammer/striker blunting. Additionally, in semi's, the slide will wear at its contact points and become sloppy.
A pistol that has under 1,000k rounds through it will go longer without needing any work than one with 10,000k rounds. Like most other mechanical devies, parts wear out on guns with alot of use.
I've seen a number of revolvers whose cylinder stop slots were extra-wide due to wear. THose guns lose accuracy and spit lead and hot gasses to the side, even more than normal. I have seen both revolvers and semi-autos have pins and springs in the trigger mechanism break. And one semi-auto had the guide rod break after a few thousand rounds. My Walther P22 had to go back to the factory twice-- I sold it after the last time I got it back from S&W. The cheap alloy frame and slide were wearing excessively. (Of course I had used it with a silencer, which gets guns unusually dirty). So yes, more shooting equals more wear and greater chance of something coming to the end of its lifespan while you are counting on it to work. P.S. I don't keep any records about how much I shoot each gun. All I could ever do is take a rough estimate. Really rough.
I wonder if anything could be learned by measuring the rifling in a new firearm, then measuring it again at certain intervals?
It's been done. You can only put so many rounds through a barrel before the bullets wear the rifling down. Magnum rifles eat barrels faster than slower shooting rifles. Some barrel manufacturing processes create longer lasting barrels than others.
+1 on that one. If you shoot hard cast lead, your barrel should literally last tens of years. The guys in guns magazine who published all those articles about WWII firearms has a gun he bought in the seventies and shot only hard cast in it and shot it a lot. He says the barrel is still very good. Thank you