matt,
I have a Win70 HVB in .243 and I'm not sure exactly what the twist is but I suspect 1-9 to 1-9.5.
I have gotten good accuracy from the 65gn V-Max up to the 95gn Ballistic Tip's. My rifle really likes the upper end (85 to 95gn) range of bullets and my longest successful shots were with the 95gn BT.
I tried the 70gn BT in three different .243's and none of them shot them well. Two of the rifles could have been iffy but my Win has shot everything great except this bullet. Duno? It may have been a bad box of bullets but I haven't bought any more to dispell this.
I recently tried the 85gn Sierra GK and wow, what a sleeper of a bullet. I figured it wouldn't be as accurate as the SMK. Yeah, right. It shoots under 2.5" at 500yds for me. I just prepped and annealed 75 pieces of brass to load up enough for the upcoming deer season.
Two more bullets that I think should be accurate and great deer bullets are the 85gn TSX and the 90gn Scirocco. Never tried them but would love to. Anyway, good luck with an awesome round and happy shooting. Keep us updated. JohnnyK.