Tinker, I tried with two means:

1. Mitutoyo Micrometer: it did measured in the vicinity of .700", both bores (maybe I am not competent enough) or because grooves and lands are not opossite. The Galazan standard 12 bore pattern gives the same stated dimension with this micrometer: .729", thus the micrometer works Ok in a round smooth surface.

2. Galazan Barrel and Choke gauge (three rounded legs 0.2" wide):

Grooves, in this position, the deepest I could go mikes .730" on both barrels (the instrument moves vertically with little friction).
Lands, in this position I tried to rotate the instrument, with some difficulty, it mikes .720", both barrels.

Thus, with some confidence I would stick with the Galazan gauge. So grooves are .730 deep and lands measure 720".

You were right Tinker, I was giving groove dimensions, at least in accordance to the Galazan gauge.

Now if this measurement is right, what would be an appropiate slug diameter?

Regards,

EJSXS