duzell, I don't even play Call of Duty. That snippet you posted? Look at the text around it. "If it can shoot crazy accuracy at 1000 yards, all the better". Not, give me something that I can shoot the legs off a fly with from across state lines. I acknowledge that for a long time the rifle will outshoot me for a very long time. I even say in the TL;DR section good accuracy is required but nothing insane like under 1 MOA. Was my post too long for you to read thoroughly? I tend to be very verbose.
Yes, I am paying very good money ($450) for a 2 day marksmanship course and it will be the first of many. Among those I have plans already to attend the Project Appelseed when it comes to my area in June. I've been out to the range 3 out of the 5 past weekends and probably put enough ammo down range to pay for the Mosin Nagant, which I've already stated I've decided against and that I want a semi-auto 5.56. Bolt actions will be looked at separately, I promise
To everybody else, I have also been looking at the M&P 15-Sport and that seems like a good answer. My local gun range has an M&P 15-22 that's fairly nice for $500. I held it but fired the Sig 552 instead. I'll probably be forced to save up for something nice anyways as there's nothing in my area right now. I went to Gander Mountain the day before I posted this and there was not a single rifle left that was even semi-automatic, as far as I could tell.
EDIT: As far as building, I am not a handy person and I would rather spend the cost of the excise tax to buy a completely built platform. I would be OK with something that can hit 2 inches at 200 yards (the longest my range allows) and paying a quality qunsmith to upgrade it IF the original platform is affordable enough. If not I wouldn't be averse to waiting a little longer to buy what may be considered middle-upper tier.