re: Advice on Breaking in a S&W 40 cal Shield Needed

You don't necessarily have to "break in" a Shield because of the way they are made from the factory, with loose tolerances and such.

The reason Kahr suggests a 200 round break-in is because they have very tight barrel-to-slide fitment. You have to get the metal rubbing together and smoothing out for everything to function as it should.

But as a rule of thumb, I don't trust a gun fully until it's seen a few 100 down the pipe. And the more you shoot it and watch it function, the more you can gain confidence in it.