you can start with necked up 303 brass. it would be around 55 mm long but thats ok with black powder. of course 405 Win brass , dont think about because 9,3x74R is easier to get here. try this guy, he would have some die sets that can be used to form the brass till it fits into your chamber before you spend the money for a custum dié set. the brass have to be reamed out for 10 mm bullets and will be very thin after. good to have one who do it before.
I would start with 10mm /.40 pure lead bullets. the right weight for the 10x60R( if this rifle is chambered for this) was 16,1 gramm for a flat nose lead bullet and the rifle may be sighted for it.I dont see 10 mm moulds over 175 grain buts maybe a simple job for a craftsman to rework such a mould.

I dont believe in a "wildcat" cartridge, this double rifle was expensive and made for a man who dont need to reload his own ammo to save money. he had have enough money to shot factory made cartridges and in special it was a cartridge he can get everywhere not only in the springer's erben shop.
thinking it was the 10x60R 400

Last edited by pwm; 06/23/11 11:11 AM.