Re: DPMS AR-15 break-in?
I don't think a break in is useful, however if the manufacturer recommends it, I will follow instructions just to be on the safe side.
With a chrome bore, Wasp is correct, just shoot it. Over time, it will change a little, tiny bit, but no where near what an unlined bore will. The chrome is in the bore to make it hard, durable, and much more wear resistant. Putting 50 rounds down a chrome bore during a typical break in won't do much at all to it.