Every gun needs to get 'shot in' a little if for no other reason than to find out what it likes and dislikes. A couple hundred rounds in a range session is a good 'get to know you' with a NIB or new to you gun. If there's failure, I want to know WHY so I can remedy the situation. For a concealed carry or self defense gun, I want it proven that it will function reliably and shoot accurately with what I feed it. Plinking and playing is one thing, when lives are on the line is a horse of a whole different color.

A buddy of mine picked up an unmodified 3 screw Blackhawk with in .357 Mag several years ago. He wanted to use it as a back up while hunting. He's a die hard reloader, so he grabbed a couple boxes of his 'pet' .357 load (using a 125gr bullet) and tried them in it and the results weren't pretty accuracy wise. After about a month of experimentation, he finally discovered that the gun shot the best with heavy bullets (158gr or higher) over the maximum listed charge of 2400 and the heavier the bullet got, the better it shot. He wouldn't have found that out if he hadn't done his homework on the range.

Semi autos are even more finicky about what they like and dislike AND you have to worry about what the magazines will feed reliably. I ended up having to change my 'pet' .45ACP load a little so it would feed reliably through all my .45's several years ago because I found that my then new Para-Ordnance pistol didn't like the 230gr load that I'd been shooting for years in all the other .45's. A slight tweeking of the overall length and it was back in business but I never would have discovered it if I hadn't carried the gun out to try it out.