Rigbymauser:
I intend to get the loads across a chronograph at some point, I am actually lead to believe the velocities will be closer to 1450’/sec (441 meters/sec)......shall be interesting.

Hi Ben,
Actually no decision....it is what RMC does. “Shotgun shells” after all?
I suppose I could have specified standard large rifle primers?

Even back in the late 1980’s, with my first 8Bore Greener rifle, I had Ray Meyer make me cases and he also used 209 size primers. They were easy then and easy now. No issues at all.

Of course the old originals are all over the map. The Brit cases used Berdan primers, and I have an original Winchester head stamp 3” 8 Gauge that takes standard large rifle primers.

Naturally any work fine with the “Holy Black”

Will try Cal Pappas’ loads of Blue Dot at some point as well.
- Mike

ADDED:
I have Mr. H. Buck Stix making me one of his star type crimp dies for these cases. That will allow me to load both sides without worry of the (left) side bullet backing out on firing the first shot.
Already have one of his in 12 Bore and it is very nicely done.