My NewEnglander .50 likes 320 grainLee R.E.A.L. bullets. When it was new I got some very good groups with T/C break-o-way sabots & XTP pistol bullets, but prefer the simplicity of the conicals. Never got great groups with patched round ball loads out of it yet, though. Thinking of trying .454 balls in sabots next.
I started with the .50 NewEnglander then added a 12ga barrel from Fox Ridge, then somehow gained a spare tang & trigger from my dealings with T/C (I think it was on a trade of a damaged FireStorm stock). I added a camo stock from Fox Ridge, then picked up a used lock on eBay. Now I have 2 complete NewEnglanders (.50 & 12ga) and they are my favorite hunting guns.