Fire forming brass

[offshore44]

I am on the verge of a stupid pet trick, and need some advice...

The oldest daughters fiance shoots a 300 Win mag, and doesn't reload. I can get a fair number of once fired cartridge cases from him. I have a 458 Win mag that I shoot a lot. 485 Win mag brass isn't cheap, and I'm always broke.

Is it reasonable / possible to blow those 300 Win mag cases out straight and make a reasonable facsimile of a 458 case out of them? How would I go about that, if it is reasonably possible?

The idea of free cases makes me smile, the idea of ruining my rifle doesn't.

[nanuk]

I have read on this

using Bullseye and COW... Weight a case full of BE, and take XXX % of that, fill the rest of the case with COW and shoot it straight up OUTSIDE.... increase the BE a grain at a time until you get straight cases.
this technique is used to create cylindrical -06 brass for the 444 Rimless

it will blow the case straight (with maybe a step at the end as the 300WinMag might be a hair longer)

I think the percent is 10% but you better research the number yourself as I am just going on a fried memory.

[elk hunter]

A friend makes all his 458 brass from 300 Win mag by loading 13 grains of Bullseye, a small piece of tissue, to keep the powder in place, and then filling the case nearly full of Cream-of-Wheat and capping it off with a wax plug. I use the same to form 12.7 X 44 from 348 brass.

[scb]

A friend makes all his 458 brass from 300 Win mag by loading 13 grains of Bullseye, a small piece of tissue, to keep the powder in place, and then filling the case nearly full of Cream-of-Wheat and capping it off with a wax plug. I use the same to form 12.7 X 44 from 348 brass.

That's what I do to make my 458 x 2" out of 350 Rem. mags, tho I use a different powder charge - but I don't think that's very important.

[offshore44]

Thanks guys! I'll give it a try and report back. Oh, does it have to be Bulleye? Or justa fairly fast pistol powder.

[paul h]

Anneal the case neck and shoulder first so they don't split when they open up.

Bullseye is the fastest pistol powder, so you don't need as much of it to get into fireforming pressure levels. You should be able to fireform with red dot, unique et al, but will have to work up until you get enough pressure to straighten out the case.

[williamwaco]

I make .38-55 cases from .30-30 cases by just loading a .30 caliber plinking load with a cast bullet and shooting them in my .38-55.

Works fine.



.

[scb]

Thanks guys! I'll give it a try and report back. Oh, does it have to be Bulleye? Or justa fairly fast pistol powder.

I was using Unique. I think I started with 5 grains or so and increased the charge 'til it blew the case almost straight. The mouth was rolled inward slightly but the expander straightened it out fine.

[offshore44]

Anneal the case neck and shoulder first so they don't split when they open up.

Bullseye is the fastest pistol powder, so you don't need as much of it to get into fireforming pressure levels. You should be able to fireform with red dot, unique et al, but will have to work up until you get enough pressure to straighten out the case.

So, I loaded up 10 grns of Power Pistol (the fastest powder on hand), filled the case with Malt-O-Meal (no COW on hand), plugged the case mouth with paraffin wax and stuffed it into the rifle. Went outside and pulled the trigger. the rifle went bang, and all seemed well. Went back to the bench and jacked the case out of the rifle.

A little stiff, but nothing alarming. The case popped out on the bench. So far so good it seemed. Picked the case up and examined it carefully. Nice and straight, though the brass looked a little "stressed" where it had been blown out. Rolled the case over in my hand and there was a crack the size of the crack of doom from where the original shoulder started to the mouth. Bummer. Examined the case more closely and realized that I had used an un-anealed case. Went back to my notes and also realized that I used 2.5 grns too much powder to start with.

Oh well, on to stupid pet trick #2!

[ricksplace]

I have used 300 win mag brass for my 458 often. You have the right idea. Anneal the case necks, 10 gr of any fast pistol powder, fill with cow or any other type of filler. I push the neck of the brass into a bar of soap to plug the end. Put the case in your rifle, point it straight up and pull the trigger. If you blow off the end of the case or crack the neck, drop the charge a little. If it doesn't quite blow out fully, up the charge a little. Once you find the right charge, you will get almost 100% of the cases to blow out perfectly.

Remember, you have a lot of trimming to do with the 300 mag cases. 338 cases work great with no trimming necessary

[offshore44]

Well, I got it to work out just fine! 8 grns of Power Pistol, fill the case with Malt-o-Meal, cap it off with paraffin and pull the trigger. It rains toasted Malt-o-Meal and out pops a case ready to trim and size. Good stuff! Thanks!

Oh, and you DO have to freshly anneal the case mouths to go from 300 to 458.

[303Guy]

Oh, and you DO have to freshly anneal the case mouths to go from 300 to 458. Yep. It's amazing what annealing can do. I annealed then sized a 303 Brit case up to 375 then back to 303 then back again several times just to see. After a few cycles the mouth wasn't so square anymore but the brass held up. (It wasn't a reloadable case - Berdan primed).

[greybeard]

Hi: I use a 9mm die with the expander plug tapered buy machinist so it fits in the 308 neck and tapers up to .459 anneal the necks and lube both inside neck and expander plug every time then trim case load with cast bullet and shoot accurate from the start and then use any load you want. Dan