I wish I could say I've never had a problem attributable to a loose nut behind the trigger.
Cold shots are finicky critters indeed, but you shouldn't need sub moa for a 200 yard shot.
Follow the directions on a can of Wipe Out, or store it with some Bore Snake Venom in the bore and patch it out before you take it out. If you think you need a couple of fouling shots, assume there is enough protection left in the pores of the bore to not worry about it. Experiment enough at the range enough to feel confident.
If you have money to throw at the "problem", it's a good enough excuse, a guaranteed result might be elusive.
Few people can (honestly) say they have never succumb to buck fever, even if it's a doe.