S & W 9mm bore measurement?

[bosterr]

I'm trying to get a good slug measurement for my friend's S&W M&P full size 9mm. It has the same 5 groove barrel they put on their revolvers. Trying to mic measure from the edge of one groove to the opposite edge on the other side of the slug isn't easy. I have 3 decent slugs made and the best I get says .3567. What slug measurement have you guys that own and cast for this gun come up with. It is not the newer 2.0 model.

[Outpost75]

To measure a 5-groove barrel:

Attachment 215503

[fredj338]

I would just size to 0.357" & roll with that. If they show leading or worse tumbling, then go 0.358". I will admit ti not slugging my bbls, I have more than one gun in every caliber but 41mag, just not practical, so go big, can't go wrong there.

[JonB_in_Glencoe]

I wrap a aluminum strip (of popcan metal) around a 5 groove slug.
Measure it, then subtract 2x the thickness of the popcan metal.

[bosterr]

I wrap a aluminum strip (of popcan metal) around a 5 groove slug.
Measure it, then subtract 2x the thickness of the popcan metal.

Thanks Jon, I'll give that a try.