Measuring Three Groove Rifling in a Trapdoor Springfield

[broken-mold]

I'm strongly considering purchasing a high quality v-anvil mic for measuring chamber casts and pound casts from the three groove rifling in my TDs. That tool looks like it would measure boolit diameters a little easier also. Does anyone know of an easier, better, (or cheaper) way to measure three groove rifling?

Also, I understand it will measure the groove diameter but what can be used to measure the bore diameter? I have tools for checking bores in shallow holes that could measure the bore at the muzzle but not deeper than that or in the chamber area.

[M-Tecs]

This addresses all your questions. https://www.texas-mac.com/Measuring_Groove_Diameters_of_Odd_Groove_Bores.htm l

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[broken-mold]

This addresses all your questions. https://www.texas-mac.com/Measuring_Groove_Diameters_of_Odd_Groove_Bores.htm l

That information is exactly what I needed but I didn't know how to find it or even that it existed.

May your tribe increase upon the earth.

[marlinman93]

Pin gauge sets are usually used to measure bore diameter. Not groove diameter, as slugging the bore will give that.