Forming 458WM from 300WM

[blikseme300]

Not that 458WM brass is hard to come by or overly expensive but has anyone on this board done this or currently doing this?

I am new to blowing out brass but read and researched a lot before dipping my toes into this new pool. So far I have formed 10 brass cases successfully doing the following: 1) Size and deprime using a Hornady 458WM FL die. 2) Cleaned using SS pins wet tumble with Dawn and LemiShine. 3) Annealed case neck. 4) Primed using LPP and loaded with 12gn RedDot, wad of TP, cornmeal to case neck and plugged with paraffin wax. 5) Fired in Ruger M77. 5) Trimmed to 2.50" & deburred and chamfered. 6) Sized & deprimed. 7) Annealed. 8) Cleaned with SS wet tumble.

What say the folks with experience, what am I missing or doing wrong?

[SSGOldfart]

Nope sounds like you got it going I don't use the wax just a small wad of TP.


Oh cream of wheat smells better when blowing out case

[Gew]

I've made 300 Win Mag into 458 Win Mag but I annealed and expanded in various dies I already had. I've blown out other cases with essentially the same steps. Good job.

[PWS]

I've done a bunch with a home turned long tapered expander fitted to an RCBS expander die. Imperial sizing wax one Q-tip swirled inside of case mouth, one stroke, no annealing. About half of what I try split on the expander but they're all range pickups used for plinkin' and dinkin' loads so I don't care. Got about 300 usable cases in not long, there are lots of magnum shooters that plink at the local gravel pits. I've used just about any belted mag, even 7mmRM with the same rate of attrition but the 7Mags are short when done. 338s, 375s, the various Wbys, whatever belted mag I find I give it a go on the expander. If it works, great, another case, if not, nothing lost...

[EDG]

Just use a long tapered expander. I have used Lee dies with the long tapered factory expander to make .416 Taylor without any issues.

[blikseme300]

Thanks for all the feedback. I'll look into the tapered expander method as it has advantages over fire forming. I have a lathe so another mini-project will be in my future.

[MarkP]

I make mine from 7 mm Rem Mag with an identical loading of Red dot, TP, maltomeal, Lars BAC to seal. The 7 mm Rem Mags are a little short. 7 mm Wby's come out about 0.004" over max @ 2.504" I neck my 7mm to 0.338" prior to firing.

I gained some length by fire forming as compared to using a progression of expanders to form 458's.

[Alan in Vermont]

Oh cream of wheat smells better when blowing out case

I thought you were supposed to use NEW toilet paper.

[cowboybart]

I lube the hell out of the inside neck and push 7 RM, 300 WM and 338WM thru a 416 Taylor die. I have to trim the 300 more but all work. About 10% have sloped or cocked ends that need trimming anyway.