I don't believe most mil spec AR barrels require a break in. They should work as well as they are going to right out of the box after a function check & lots of lube.I would take an AR for that with Anderson or PSA receivers. With the "Right Stuff". Match barrel, drop in trigger,enhanced mil spec upper/lower kits ,cool rail, M4 feed ramps, and magpul STR stock (depending on length of barrel). From the right ODT Members (or willing to come out and run it) . With 60rds steel cased ammo down the barrel with no hiccups . But that's just my opinion. Note for newer newbs= I clean the barrel after each of the first 5 rounds and after first mag ; others may have a better routine for breaking in a rifle? NO POLY for me
@BangBang says women are the same....