My impression here of what some customizing of automatics (mostly) amounts to is doing things to the gun that a certain amount of normal use will produce anyway after a while. Usually a gun will smooth up after it has been fired for a while, which leads me to believe that the Nagant revolver I had was virtually brand new--and the Colt revolvers were all nearly so. But anyhow, when I get home tonight, I'm going to see what all the manuals I have say about it. I don't recall that any mention a break-in period.
I also wonder what those WWII issue .45 autos were like when they were still new in the box, although I also suspect they may have had a closer inspection than we may give them credit for having today. And perhaps a better inspection than guns get today.
I also suspect that 500 rounds may be more than is necessary to break in a new gun. Most of my guns were never fired that much if I bought them new, although I made up for it with others.
I also wonder what those WWII issue .45 autos were like when they were still new in the box, although I also suspect they may have had a closer inspection than we may give them credit for having today. And perhaps a better inspection than guns get today.
I also suspect that 500 rounds may be more than is necessary to break in a new gun. Most of my guns were never fired that much if I bought them new, although I made up for it with others.