Daryl

I was always under the impression that the "Bore" was the Major diameter and the size of the bullet fired. ie in a 470 NE the bore is 0.475" and that is the size bullet fired.
The "Lands" or rifeling stands proud of the bore and engrave the bullet and the tops of the lands form a circle, Minor diameter.
I agree with you that the bore can also be refered to as the Groove diameter.
Maybe I have been wrong all this time.

The point is I agree that the rifeling is not very deep and at 2 1/2 Thou I will defenitely be planning on shooting slightly oversized balls and right sized slugs.
I will be ordering a custom sizer die that will allow me to size my slugs to the exact bore size.
They are currently coming out of a custom mold that throws them at 0.618" and 0.625", 2 cavities.

Well there is only one way to find out, and that cant happen for a few months.

Thanks
Nitro