I bought a half dozen letter C Drill Bits from a local tool supplier today and didn't take my Mic.
I need them to make the primer pocket in some bushings I put in 50 BMG cases.
Letter C is .242. Mt last one from McMasters that I broke, was .242.
These are .247.
I'm as mad at myself as them. I drilled it ASSUMING they were correct and the primer falls out.
Won't make that mistake tomorrow.
I always tell my guys to measure every tool they use. Load a bunch of wrong-sized tools in a CNC, and make flawless junk. Drills and reamers get tossed in the wrong drawer, or in your case, they're just sized wrong (?!) In my trade- toolmaking- .005 is a football field, relatively speaking.