A reasonable cartridge is a 30-30 blown out to .401. About the power of a T4 with out the recoil.
JES Rebore could do the.405.
Some years back I had a single shot Austrian rifle. Break down, Hammerless. I didn't have it very long and didn't own cartridge for it.
It was a 9??mm x 72 with rim. It was straight rimmed. If I had it I could use it. T.S.s 9.3x 74R I don't believe would slide by with the wardens. It's easy to see base is larger than bullet. They would be calling it a bottle neck. A guy up in next county was using some old
38cal cartridge a couple years ago. I guess it had a visable taper and he got fined for it. It just depends on warden if he wants to get chicken poop.
We have also got to have written permission from the landowner. I run into old guys that will let you hunt all you want but they will not
sign their name to a permission slip. Wardens are tough on this even though there has been no complaint filed. You better have the legal gun, legal ammo, a watch and a pencil in addition to written permission if you want to avoid a hassle.
Left to Right: 44 Mag, OEM 444, SG 444, and the MIGHTY SSG 444 (9.3 X 74R necked up to .429).
How about a .444 Rimless, based on the 30-06 case. Headspaces on the mouth of the case. Its covered in 'Cartridges of the World'.