S&W .45 ACP revolvers have "G.I. Joe" specification 6 groove rifling with narrow lands and a bit shallower groves than S&W's usual 5 groove revolver rifling which has lands and grooves of about equal width. Your guess at .005" is about what I would have guessed it was designed to be. G.I. Joe .30-06 and .308/.762 rifling which was designed in the same time period ideally has .004" deep grooves. I'll bet your 25-2 shoots more accuratley than you do.