I "think" I would concur with you on a .50cal. Also I "think" that if you polled every one of the 213 shooters on the firing line at the York Shoot last Saturday a .50cal would have been #1. I know years ago when I went into heat about getting into the chunkgun circut I asked this same question of Lowell and Joel Gard, Ron Ehlert, The Dribblers, Ralph Walker and several others who were amoung the best shooters and while it wasn't 100% in favor of .50cal it came close.
I'll say this, and I'm sure it's excellent advice: Pick up the phone and call Paul Griffeth, ask him, and see if HE will build you a barrel! He has won three of the last four York matches and six of the top ten shooters last Saturday were using his barrels. He uses a 1:66 twist though I don't know the cal, .50 I think. His rifling is not square or round in the furrows,but is angular instead. I don't think this difference is at all critical popping squirrels in the head, but like Many Klatch says....when .001" seperated #1 from #2, it does!
The York Shoot last Saturday was a BLAST!! Wish I didn't live 6-7 hundred miles from the Chunkgun Circut :shake: