Good day everyone,

I own a rifle chambered in .338 RUM. Purchased cartridges are expensive!
I have found a local source of once-fired .300 RUM brass that is more affordable. I also know that the .338 RUM is based on the .300 RUM(aka .404 Jeffery)
What expander dies do I need to resize them to .338 RUM? Is it a multi-step process?
This is new reloading territory for me. I need advice.

tazzman

Well sounds good but you have one big problem. The 300 RUM is a 2.85 inch case--the 338 RUM is a 2.760 case! One can shorten necks, but in this case the shoulder comes into play and starts at 2.296 on the 338 and 2.387 on the 300! I don't believe you are going to be able to work that out too easy! Not as simple as just necking up!

I think the best thing for you to do is bite the bullet for 338 RUM brass.

Michael

Your 338Rum die should handle the neckup fine. The 300 case will shorten a little when you neck it up it will still need to be shortened. The new shoulder might not be fully formed and yes you will have an old neck junction in your neck. I've had it cause issues I've also had it work fine. Anneal maybe ream or turn the necks.

As michael said not just a straight neck up. I would really think about how much my time was worth. Second you are talking about starting with once fired brass. That brass has been thinned. How much you don't know. In what areas you don't know. For my $$ I would never start a forming process with once fired brass.

I can't believe the nay-saying I'm hearing here. Just lube appropriately (including the insides of the .300 necks) and run into your FL .338 UM sizer (assuming the expander button has a reasonable taper to it that allows it to enter the undersized neck), then trim to length. If the expander button is too blunt, go get an 8mm expander button and do the necking-up in two steps. Any remants of the old neck/shoulder will be only cosmetic and will iron out on the first shot. Unless the orginal brass started out pretty hard in the neck area, it won't need annealing, but if it is too stiff to rework easily, go ahead and anneal.

StoneCreek

Well I am going to have to eat everything and choke on it! YOU ARE CORRECT! I did it in one step--took a 300 RUM and done nothing but run it thru my 338 RUM Size die, trim it and put it in my Win M70 338 RUM. It is a VERY tight fit, closing the bolt with some difficulty, however I am 100% convinced when fired it will form to the chamber and the brass will be formed and fine at that point!

Tazzman

Gotta back up some on my part. My honest feeling would have been that it would have crushed the shoulder, but it did not do so to my surprise! I think you can do this if you want.
Not multiple steps either--like I said, just run it thru my 338 size die-and trim to length.

StoneCreek

Thanks for the challenge and thanks for letting me learn something new today!

Michael

Stonecreek is right. Lube them, run them through your .338 RUM size die, trim them, and they're ready to load.

Anealing shouldn't be necessary, but it doesn't hurt.

A few months ago, I found 48 once fired .300 RUM cases at our local range. I also had a couple of 7mm RUM cases that I had found. I made myself a long taper expander plug from a 7/16" bolt that fits in my RCBS .375 RUM size die. I use Imperial sizing wax, lubed the found cases (including inside the necks), and opened all 50 cases to .375 RUM in one operation. No splits or other problems.

quote:

I found 48 once fired .300 RUM cases at our local range. I also had a couple of 7mm RUM cases that I had found.

Just curious when you find brass at the range how do you know it is once fired? Besides I've left once fired brass on the range that I sure wouldn't use a second time. I know a lot of reloaders pick up brass on the range for their use. I simply don't. Why go to the time and trouble to form brass and not start with new.

quote:

Just curious when you find brass at the range how do you know it is once fired? Besides I've left once fired brass on the range that I sure wouldn't use a second time. I know a lot of reloaders pick up brass on the range for their use. I simply don't. Why go to the time and trouble to form brass and not start with new.

Call it an experienced guess. I've been reloading (and scrounging shells) for over 40 years. I inspect all cases before and after reloading. With these .300 RUM cases that I picked up, they looked new, not reloaded. The cases all had that shiny new look, no sooted necks, no re-sizing marks on the sides, no multiple bolt face marks on the back of the case, the primers were the same shiny brass color as the cases, there were two brand new looking Remington .300 RUM cartridge boxes on top of the trash in the barrel behind the bench, and at about $1 per case, no reloader is going to leave 48 new looking cases scattered on the floor of a range.

I have also thrown away cases at the range, but those cases did not in any way look new, and it would be an occasional case, not 48 at one sitting.

And as for the time it takes to re-form the cases, well I've been doing that for 30 years with my .30 Gibbs and .257 AI. I like to tinker. Besides, it's something for a retired guy in Montana to do in the winter while waiting for global warming to melt all this white sh*t. And it probably took me as long to write this reply as it did to resize those 48 cases.

quote:

And as for the time it takes to re-form the cases, well I've been doing that for 30 years with my .30 Gibbs and .257 AI. I like to tinker. Besides, it's something for a retired guy in Montana to do in the winter while waiting for global warming to melt all this white sh*t. And it probably took me as long to write this reply as it did to resize those 48 cases

I shoot more AI and pure wildcats requiring forming than I do factory. I just feel if I'm going to go to the trouble of sizing, necking up or down and then fireforming I choose to start with a new case. Heck 90% of mine come from the same lott of Norma brass.

If it works for you go for it.

Hi everyone,
Thanks for all the advice. I really appreciate the experimentation some of you performed on my behalf.

Hopefully will talk again later,

Tazzman