It flat out doesn't. In order for a mil-spec lower to be mil-spec it must be 100% identical to every other mil-spec lower (besides markings). It has to be made of the same alloy, made to the same tolerances, and given the same finish. Any differences would mean it's no longer mil-spec. The only functional difference between any two mil-spec lowers is how much you paid for them. That being said, the 'lower end' mil-spec lowers tended to have their finishes applied better than Colt's AR lowers back when they sold them to us lowly civilians.If my lower parts are all quality, how does the stripped lower play into the equation?