Slugging a 5 grove barrel

[Catch]

I have slugged a few barrels but this one has me confused. Anybody had any experience slugging a 5 groove barrel. It seems impossible to get an accurate measurement. Need some help...........Thanks:

[oneokie]

Use a piece of shim stock or beverage can to wrap the boolit/slug. Measure the thickness of what ever you use to wrap with. Measure, then subtract 2 thickness of the wrap. A light touch on the mic makes for more accurate reading.

[Morgan Astorbilt]

Check around for a machine shop that has a 108º V-anvil micrometer used for measuring 5 flute end mills. They are what you need for the 5 groove slugs. They're less common than the 60º V-anvil micrometers, used for measuring 3 flute end mills.
Morgan

[leftiye]

The biggest measurement you can get is the right one. The leading edge of one groove on your slug and the trailing edge of the opposite groove are actually opposite, and full diameter. Your micrometer will try to "walk" off of these edges of the grooves, so you have to be sure to be right on those edges.

[462]

Another way is to slowly rotate the slug inside the jaws of a caliper, as you ever so gently keep pressure against the slug. Be careful, though, as the slug is soft and you don't want to deform it.