I don't know that I ever worried about breaking a gun in. As soon as I get one, I clean it, sight it in, then clean it again. The next shot after that will either be to test handloads or shoot game.

I used to shoot 3-5 bricks of .22lr through my old .22 a week. I didn't break it in, just cleaned it after about every 100K rounds. It still shoots true.