I'm sure this has been discussed somewhere on this board before, and there are plenty of websites that discuss it/show it. I have formed .577/450 using only the Lee .577/450 sizing die, and it was quite time consuming. It took me about 4 hours to form up about 17 MagTech cases, ruining 8 in the process.
After watching this video, https://www.youtube.com/watch?v=rDRnSOrPbho I decided to look into getting an intermediate die to make the process go a little quicker. So I got a die off eBay which takes the case down to around .560". I had to start with the .577 Snider die to get the case to enter the intermediate die, and that got the job done fairly quickly without a lot of problems.
Setting the .577/450 die up, I went in small steps, but I still get to a point where the case develops wrinkles and at that point it's pretty much wrecked. Now I've tried this just annealing lightly, annealing where the case mouth is cherry red, but it's still not working too well.
It seems as though reducing the diameter in steps of .025" at a time or so would be the best way to tackle this job without ruining brass at a buck a shot: when you can find a vendor that has it in stock...
I'm just curious whether there is someone who might make say a 5 or 6 die set of forming dies stepped to do what I described above.
And yes I know that there's Captech (former Jamison) - they might do a run this year... or the guy that sells the formed hulls, or 28 gauge CBC hulls...
Thanks!
Craig