[Charlie Z]

I can't remember if Marshall's Tech Book has it, but I stuck a bullet in the carbine today and poked it out. So, now I can say that I've slugged the bore. Question is how do I measure the slug?

I've got a nifty new digital micrometer and when I measure the barrel groove off of the flat of the slug, I consistently get .4295" (.44mag). If I turn the slug a bit to hang on the edge of the flats, it shows .4311". Which is the right measure?

 

[MikeG]

Charlie,

They might both be correct. It is possible that the depth of the groove is not consistent all the way across. For that matter, the individual grooves may not measure the same.

I would just take several measurements and average them. In this case, the maximum number you are getting is over .431", so if you were to order bullets for the gun, I'd personally start with .431" or .432".

Just as important as the slug measurement is how smoothly it went down the barrel, once it was engraved in the rifling.