Re: How good is good enough?
Factory loads have a purpose, and some of them do especially well.
I have tried duplication in the past, and generally found that original, basic load development, unrelated to any other load, achieves the best results. It boils down to whether I want to chase only one goal, the best <span style="font-style: italic">I</span> can do with the specific rifle; or whether I want to also add the goal of duplicating somebody else's work as well. Keep it simpler and prosper.
I will generally attempt to make an educated guess according to multiple load data sources, then bracket that load in increments of (for .308) about .3-.5gr, a pair of 5 round groups per increment, five increments max. I save a second round of increments for bracketing the most promising increment by smaller increments. If I did it right, it took only about 100 rounds max. If I manage .5 MOA on the first round, so be it; I'm already there.
My goal is simple, .5 MOA or better, whichever comes first. Getting more anal just costs bore life unnecessarily unless I'm a BR devotee; and in that case, I'm on the wrong site here.
Good shooting, especially LR shooting, is about the shooter. IMHO. Given the same equipment and ammo, one shooter will do better than the next. After a lifetime of shooting, I've concluded that once the rifle can achieve .5 MOA in the Short Range environment, it's good to go. As long as that's a given, upon which we can rely; the rest is mental and physical, and not mechanical.
The remainder of the excellence comes from the shooter's understanding of where the increments of accuracy and inaccuracy originate in their technique. If you concentrate on the inconsequential you waste enough of your concentration to ensure failure. There's a lot of things to consider, and narrowing down your concentration to the significant ones will render an impossible task into one that is worth attempting.
Let's be honest. For the average street inhabitant, hitting a 2 MOA target at 1000yd is an impossibility. Just once, and we are tasked to do it with regularity. The training, which must encompass thorough understanding of the how and the why, makes our difference.
Greg