Hello fellow members,

I have a question regarding the procedure involved in necking up 300 RUM brass to .375 caliber...

I'm getting one of my rifles re-barreled into a 375 RUM, and I was thinking, how hard would it be to neck up the 300 RUM brass just in case the 375 brass becomes hard to get by at times? Can I run the 300 brass directly into a 375 FL sizing die and call it a day or do I need special equipment?

Thanks in advance.

Maurice

Use intermediate steps like a .338 expander button followed by a .358 expander button. Of course, if you can find a tapered expander that goes from .308 to .375 then a single step is just as good.

Going from .30 to .375 will probably work, but you will lose some neck thickness and run the risk of neck splits. Necking up usually results in slightly less neck wall consistancy than necking down, but as I understand it, you are talking hypothetically about being caught in a situtation in which you have no other brass to work with.

If the brass is not new you'll want to anneal it beforehand to assure proper ductility.

Thank you Stonecreek for your reply. Yes you are correct. This is hypothetically, just in case I run out of 375 Brass. I have a few hundred cases right now, and will stock up for a lifetime...