I know . . . .458WM brass is cheap. But I keep finding handfulls of 7mm brass at the range. I was wondering if I could fireform this brass to .458WM for use in reduced cast-bullet loads.

I've made 9.3x57 from 8x57, but that was a much smaller jump in neck diameter. I think I used 10gr of Bullseye - some toilet paper - a case full of grits - and some more toilet paper. It worked pretty well.

Would a similar system work to make .458 out of 7mm? Any experience here?

Thanks,

Bob.

WOW, that's a large step... but, iirc, hogkiller has fireformed 300wth to 458 lott.

if it were me, I would anneal the cases first

then start with 10gr, and work up till you had a good load to pop them.

the case length will probably be off, when you are done

j

Would you expect the cases to be shorter or longer?

Annealling the case mouths is a must. I did make some 458 Lott brass from 300 Wby. It was a trial just to see what would happen. These were old cases that had been loaded several times. I did not anneal them and lost nearly half of them to splits. I used the good ones to form dummy rounds.

10.0grs Bullseye should be a good start. Fill cases with cornmeal or grits, then top with a small amount of tissue. Good luck.

Hog Killer

Anneal case neck and shoulders with a torch. Use 15-20 grs of bulleseye, covered by oatmeal and a soap plug in the case mouth. Hold the muzzel up in a clear place and fire it. Out will pop a perfectly fireformed .458 win. Ususally bcases lose length by this process.-Rob

Thanks for the help guys!

Aneal and blow them out. You'll probably find they come out about 0.02" short. 300 win mag would be a better option, less to open up, and a tad long so perfect to trim to length.

Don't be suprised to see several of them split, even if they are anealed.