Fire-forming reduced loads for RUM

[RUMt]

I have three 300 RUMs, two 338 RUMS and a 375 RUM. Given they burn at 63K PSI the brass can only be reloaded about 3 times. I'd like a reduced load I can use for fire-forming + plinking. My Speer reloading manual (#10, 1977) has reduced loads using SR 4759 (RUM not invented yet) - and the latest Speer manual (#14) is sold out.

I'd like some reduced loads that won't take away one of the 4 lives of the brass. I know that reduced loads don't guaranteed reduced maximum pressure, but I should be able to find a load that can be used for target shooting + fire-froming + not stress the brass.

[Michael Eichele]

90.0-95.0 grains of H50BMG under 178 AMAX's in the 300 RUM are good accurate mild loads.

If sized properly, you sure can get more than 3 firings from an RUM case.