I've never seen any DRT difference between flat-based and boat-tails. I've used both for some forty+ years. ,243 and .30-'06.
I've never seen any notable difference in group sizes, either. That's with hunting rifles which mostly shoot somewhere between 1/2 and 7/8 MOA. I used to have an old Ruger 77 heavy-barrel .220 Swift. I used exclusively the Sierra 52-grain HPBTs. Five-shot groups of 3/8 MOA, darned near every time I checked. Dangfino.
You're from BATFE? Come right in! I use all your fine products!