Forming 6.5mm WSM Cases

Cases for the 6.5mm WSM are formed from 270 WSM brass, manufactured by Winchester.

.288 = Normal neck size bushing
.289 = Alternate neck size bushing ... haven't tried

.305 = Necking down new brass, first step
.300 = Necking down new brass, second step
.295 = Necking down new brass, third step

Since this is a wildcat cartridge, I have to form brass for it. We start with 270 WSM and neck it down. We used Redding Type S neck sizing dies, starting with a .305 bushing, then .301, and then (I believe) a .295 bushing. The diameter of the chamber's neck is .292, so we set up the neck turner to cut the necks so that the neck diameter of a loaded cartridge was .290 (or .2896, actually). I should probably get a drawing of the reamer dimensions from Lou for my reference.