Originally Posted by davewilson
A 25RUM....are we feeling the need for speed?
don't claim to know for sure, but i'm under the impression that the shoulder height(headspace) may be different. some bushings seem to go down over the shoulder/case wall intersection and some seem to start somewhere on the shoulder surface. not sure which RUM case you're using but the 338 is a little shorter which is not a big deal. just make sure the shoulder surface is complete on the bushing or you might have a step on the shoulder of a sized case.
Ha! A guy at the local gun shop asked why I wanted a 25 RUM. My reply was I wanted my bullet to strike the 600 yd gong before his, even while letting him fire first.
He shook his head like he was expecting a more adult-like answer.
I neck down the 7mm RUM case to 25 caliber for this cartridge and it's ready to go. Well not quite. There's also the standard uniforming of the primer pocket, inside deburring the flash hole, outside neck turning, annealing the case necks, cornmeal fireforming to pressure fit the cases to my chamber, trimming to uniform case length, VLD deburring the inner case neck and deburring the outer case neck.
The case body and shoulder angle on all the RUMs are basically the same to my knowledge, so I think the 338 RUM bushing neck sizing die would be completely functional with the proper sized bushing for the 300 RUM, 7mm RUM or my wildcat 25 RUM.
I already have a custom Redding full length sizing die. But I also want the option of neck sizing only - using a bushing die. I'll study my 338 RUM die setup tonight by unscrewing the top half of the bushing neck sizing die to see where my 25 RUM case neck/shoulder junction is positioned with the RCBS press ram in the proper up position. As long as the neck/shoulder junction clears the recess that the neck bushing bottoms out on in the sleeve, I think this sleeve and die will function properly with a 257 neck bushing.
Thanks for the input to date. I'll see if I can't get ahold of Redding Tech staff by phone again tommorow.