The NM are better in lacking hammer notches and sears which can break, being essentially an overcenter lock, downside being it quit being all coil spring in the flat bobby pin loading gate spring which has been rarely known to break, and twisted or overthick-topped transfer bars which also have been known to sometimes break...but parts still available in the uncommon instances of breakage. I have been shooting my NMBH .45 since 1976.The NM, with the transfer bar safety, is a work horse and nothing "wrong" with them. BUT, a 3 screw is just perfection. Regardless of caliber, I covet every one of them find.