Brass for 375 RUM

[Dave from MN]

I recently purchased a 375 RUM, but I am unable to find any brass for reloading. I have gone to all of traditional sites and have listed my name to be notified when they finally get some brass in.  In the meantime, does anyone have any experience in using 300 RUM brass and simply expanding it to 375? I believe the cases are the same size - just with a different neck diameter. Do you need a special resizing tool, or will the 375 RUM reloading dies work? Does the brass need to be heated before resizing, or will reloader lube suffice? Any insights would be greatly appreciated. Thanks!

Dave from MN

[yorketransport]

You can use 300 RUM brass, but it's not much easier to find! You may want to neck it up in two steps; 338 first, then 375. 30-375 is a pretty big jump and you'll probably split the necks. Also look into using a tapered expander like the ones from Hornady. I use one when necking 223 brass up to 7mm for the 7 TCU and it gets the job done in 1 pass and I've never lost a case. The standard expander cost me about 5% of my cases.


The other option is to use 404 Jeffery brass. It's usually not cheap but there is some top quality brass out there. I have a 375 RUM improved that I designed and I've used both 375 RUM and Norma 404 brass for it. The 404 brass is much better quality and lasts significantly longer than the Remington RUM brass. Just neck it down in the 375 RUM die and fireform with Bullseye and Cream of Wheat. It's worked well for me.


Andrew

[Dave from MN]

Thanks for the reply, Yorketransport. I appreciate your insights.