Hey Stan,
In case you were curious, I measured some new Nosler brass, rim diameter .524", rim thickness .054", head diameter .464", length 2.93".
I had a similar thought as what you're thinking, but other little projects, happen. If you aren't in a rush, monitor the Nosler website, it seems they just had a sale that puts the cost of their brass, at about what you're considering with the Privi brand. I never loaded any, but I recall figuring out that a 41 mag seating die would put enough of a crimp to hold an overshot card. I was going to try filling the bullet seating cup with epoxy, so it would be more or less flat.
I may have read it wrong, but you mentioned opening up the primer pockets? Why not just use large rifle primers? Anyway, best of luck with the project.
Stan
Can you tell us the source that says you have to trim the case rim thickness? All the sources I have found show that the 9.3 round is a tiny bit smaller in both diameter and thickness than the 410 and the base is nearly the same diameter. Also, the comments I made about primer posckets had to do with converting MagTech particularly to LR from SR. Using 9.3 cases manufactured with LR primers should require nothing. Simply get a case and see if it fits and pop a primer. I would do it for you but I sold all my cases with my last 9.3 Ruger. I did at one time load some 45/120 cases with shot for a Ruger No.3 I rechambered to that caliber. The idea was survival loads with a large bore. They shot surprisingly well with an open pattern of course, and I shot a couple of doves as a proof of concept. Worked like a charm with standard 410 loads.
I would post a request in the Double or single shot rifle area and ask if someone can send you a case. A lot of people here own 9.3's I suspect. Better yet simply ask someone to insert a 9.3 case in a 410 and see if it fits and cycles.
In all these posts, I haven' seen any comment that anyone has tried this. I think the solution is too simple to worry about. Put Unique, Herco or some such load in a case, fill it with cream of wheat, plug it with a bar if soap and fire form it.
