ah yes, if i could read the whole question...
Then 9.3x74R cases can be cut/trimmed and fireformed to make full, 3-inch 410-bore shells!
What i have read to do is take the brass, and load with a full powder charge, top with cream of wheat/rice, and seal with wax.
Point somewhere safe and fire. It should blow the case walls out straight to conform with the chamber of your gun.
I can't find too many loadings for it but here's a start:
CCI 300 large pistol primers
13.1gr Lil'Gun
1/8" fiber wad followed by a WAA41 plastic shot wad
3/4oz 7 1/2 lead shot
.030 overshot card covered in Elmer's glue
Hope that helps,
C-