Daryl

The guy who I buy my balls and slugs from, I do not want to cast myself,
Makes a 0.627" RB that is pretty close to 350 grains, so Lyman slug data is a good staring point.
He also makes a "Hammer head slug " from a custom mold 0.618" and 0.625" that weigh 1 0z. (440 grains )This is most likely what I will do most of my shooting with.
I will have to develop a load for this, since most surrogate slug data does not go higher than 350 grains.
This is where I will ahve to use surrogate brenneke data or heavy field load lead shot data and work up watching for pressure and velocity.

I think that I will buy some factory ammo and do a little investigation, through disassembly.
In the hopes of finding the largest (Close to full bore) heaviest slug to do the regulation with.
That way if I am forced to use factory ammo it will be the closest to my loads and as you have said why shoot sub caliber bullets in a big bore gun.

Nitro