I do the same NBT/NAB swap out with my .300 WM; 180 NBT's for targets, NAB's for game. I found NBT's to have a slight accuracy edge over NAB's, but not enough to make a big difference.

The .30 cal. 180 gr. NAB and NBT have the same B.C., ogive, seating depth, POI, etc.

With the new NBT's, maybe not that much terminal performance difference; with vintage NBT's, a good bit of difference.

DF