Fire forming 458 Win Mag.

[15meter]

Buddy is looking at a 458 Win Mag. He's got a good supply of once fired 338 Win Mag. In 458, silly elephant killing monolithic solids left over from a previous rifle he sold. Crazy to shoot them just to get brass. Even pulling the bullets is a little silly, he crazy enough to go back to Africa again.

Has anyone fire formed 338 to 458? 300 Win Mag? 7mm Win Mag? Have all three in the drawer.

I've blown out a number of other cases over the years. 30-30 to 38-55 being the longest stretch that I can remember.

Curious if anyone has done it and what your recipe was.

When I was doing it before it seems ~10 grains Unique, toilet paper, screenings from under the grain dryer(free as opposed to buying corn meal, and they are starting to shell corn around here) and either toilet paper or a 1/4" thick wax plug.

Wax plug seemed to work a little better, along with having the rifle vertical when firing.

Anybody?

[Nobade]

I had a lot of cases split when trying to fireform them up to 416 Taylor. I finally gave up on that and made a set of expander mandrels to go up one caliber step at a time, and annealed the cases in between steps. That did the trick and I didn't lose any more cases. You can certainly try the cream o wheat trick but is didn't work for me.

[Mk42gunner]

I've never had good luck fireforming cases without a real projectile in them to build pressure. And in these days of scarce and high dollar primers, I would rather expand them on the press.

A tapered expander has no problems going from .270 Win or .30-06 to .35 Whelen in one step, I would imagine you can find or make something similar for the .338 to .458 Win Mag. Might have to take it in two steps, it is almost an eight of an inch difference.

Robert

[dh2]

with the cost of a trip to Africa, why would you try to skimp on the brass. And do you want to take any chances on a 1500 Lb. cape buffalo charging after a bad hit and you just hope that your penny pincher case feeds and functions flawless? I bought 100 rounds of new .458 Win Mag. brass 25 years ago, and still using it, you will not shoot a .458 Win Mag enough to wear any thing out. My 375 H&H Mag is only 15 years old and on the same deal.

[pworley1]

I have made them using different plugs to expand them. On the 338 to 458 I only had to use the 416 expander as an intermediate step. The 300 win mag can be used but will be a little long, while the 7mm will be just a little short but will work fine,

[15meter]

with the cost of a trip to Africa, why would you try to skimp on the brass. And do you want to take any chances on a 1500 Lb. cape buffalo charging after a bad hit and you just hope that your penny pincher case feeds and functions flawless? I bought 100 rounds of new .458 Win Mag. brass 25 years ago, and still using it, you will not shoot a .458 Win Mag enough to wear any thing out. My 375 H&H Mag is only 15 years old and on the same deal.

But this brass is intended for plinking loads, not serious hunting.

Cast boolit dinger ringing, water jug blowing up kind of loads.

And my primer/powder stash is good enough, I suspect my daughter will be taking my name in vain when I'm either dead or drooling in my soup at the county farm.

Based on my use of various and sundry calibers like 300/375 H&H, 450, 400, 350 N.E. and two or three dozen other less than common calibers the likely hood of making 100 pieces last 10 years let alone 25 is pretty remote.

If I can recycle freebie brass into something I can use, it just lets me and my buddy shoot more.

And I like the challenge of it.

[elk hunter]

We made quite a few 458's out of 300 Win Mag several years ago. Annealed the neck and shoulder loaded with about 13 grains of Bullseye and topped with corn meal and a wax wad. We had a few failures but the cases were free. The friend we made them for
used them for at least ten years and as far as I know never had a problem.

[15meter]

We made quite a few 458's out of 300 Win Mag several years ago. Annealed the neck and shoulder loaded with about 13 grains of Bullseye and topped with corn meal and a wax wad. We had a few failures but the cases were free. The friend we made them for
used them for at least ten years and as far as I know never had a problem.

Annealed first? I was going to try fire forming first then annealing. Seems I have had better luck annealing after forming, I'll have to give it a try.

Thanks. And I've got a bunch of ancient bullseye, that should work wonders on fire forming.

Did you re-anneal after fire forming?

[elk hunter]

Annealed first? I was going to try fire forming first then annealing. Seems I have had better luck annealing after forming, I'll have to give it a try.

Thanks. And I've got a bunch of ancient bullseye, that should work wonders on fire forming.

Did you re-anneal after fire forming?

We may have re- annealed the brass after fireforming. Sorry, I just don't recall. Nor do I recall how soft we went on the initial anneal. The hotter you get the brass and then quench, the softer the brass becomes. Too soft an anneal can cause the cases to crush when seating a bullet. New or once fired cases generally give better results as many people full length size fired magnum cases thus setting the shoulder back which will accelerate case separation in front of the web. Belted magnum chambers, at least the early ones, were made quite generous in length and the shoulder can move ahead on firing quite a ways. The British, i.e. H&H, who came up with the belted case, were not concerned about case life beyond the first and presumed only use. Not many people reloaded in those days. A few years ago I made some 11 MM Mauser cases out of 300 Win mag using the same technique.

Hope this helps.

Elk Hunter

[RustyReel]

I made a few out of 7mm Rem Mag brass several years ago just to see if it could be done. Used whatever dies I had on hand to expand the neck and finishing with the 458WM dies. Necks were not pretty but they worked (cast boolit loads). I use 7mm Rem Mag brass to make cases for my .458 American (ie 458x2") by trimming at the neck and running thru the 458 WM die. I have also fired quite a few 458 Americans in my 458WM's, again just to see if they would work. Kinda like firing a 458WM in a Lott. Try it at your own risk.

I think the .300 Win Mag cases are a little easier to convert because they are a bit longer, but I never had many extra of those to use. 7 Mag brass was cheap.

[15meter]

The rifle arrived yesterday, first try at making brass was going to be fire forming 338 Win Mag. Won't chamber easily. Suspect the rifle they were fired in had a fat chamber and I won't see the 458 dies until sometime next week.

Plan B:

Full length sized 3 7mm Rem Mag. 13 grains of Bullseye, TP/cornmeal/wax plug, then BOOM!

Then 3 split necks.

Plan C:

Anneal a couple of 7mm mag, full length size to get them to chamber THEN the fire forming load. That's tommorow.

If I had 300 Win mag dies to size with I'd start with 300 Win Mag.

[richhodg66]

When I got a .458, I just posted a WTB and got enough brass to last quite a while at the rate I shoot it. I'd try that before I went to all that trouble.

It's a really fun cartridge, though. Everybody ought to have one.

[Wayne Smith]

The rifle arrived yesterday, first try at making brass was going to be fire forming 338 Win Mag. Won't chamber easily. Suspect the rifle they were fired in had a fat chamber and I won't see the 458 dies until sometime next week.

Plan B:

Full length sized 3 7mm Rem Mag. 13 grains of Bullseye, TP/cornmeal/wax plug, then BOOM!

Then 3 split necks.

Plan C:

Anneal a couple of 7mm mag, full length size to get them to chamber THEN the fire forming load. That's tommorow.

If I had 300 Win mag dies to size with I'd start with 300 Win Mag.

Backwards - full length size and then neck anneal. You might want to do at least one expansion before neck annealing. Expand neck with whatever expander buttons you have to get it closer to your goal. Remember, brass work hardens. It will be a lot easer to fire form from, say, .375, than from 7mm.

[15meter]

Backwards - full length size and then neck anneal. You might want to do at least one expansion before neck annealing. Expand neck with whatever expander buttons you have to get it closer to your goal. Remember, brass work hardens. It will be a lot easer to fire form from, say, .375, than from 7mm.

Which is what I did, just wrote it up backwards, I've crumpled enough shoulders to know that, just not smart enough to put it down on paper.

Plan C was in actuality:

1) 7mm Mag, F/L sized with a 300 H&H, then 375 H&H, THEN anneal. Then fire forming load. Success #1

2) 300 Win Mag, F/L sized with a 375 H&H, THEN anneal. Then fire forming load. Success #2

3) 338 Win Mag, F/L sized with a 375 H&H, THEN anneal. Then fire forming load. Even I figured out that step with the 300 H&H would probably be kinda pointless. Success #3

4) 7mm Mag just annealed then fire form load and KABOOM. Success #4.


Think I got this figured out, as for buying the brass what fun would there be in that? Gives me practice for the weird brass that I need and either are stooopid expensive or flat out made out of Unobtainium. Like 280 Ross or 7x61 S&H. And we ain't talking Green Stamps here

Already have 60 pieces of 338 Win Mag necked up and back in the polisher, anneal tomorrow night.

And as an added bonus I got to watch Bela Lugosi in White Zombie from 1932 while I was prepping the brass.

Good way to spend an old geezer Saturday night.