I was just looking around the reloading stuff to see what might work. The neck expander from a .357 Magnum die might at least open the mouth enough to get a .375 expander ball started. The .357 expander will just start to fit inside an 8x57 case mouth, although it's not long enough to fully expand a .30-30 neck all the way down. I also have a Lee Universal expander, it comes with two straight tapered expander plugs and the larger one goes up to .45 caliber so it would certainly open a case mouth enough to get a .375 expander started, but it's a steep taper so it doesn't give a normal .375 expander ball much lead in.
The problem as I see it is supporting the somewhat thin .30-30 case during all of this so the shoulder doesn't collapse. Anyway, it's worth a try just to learn if it will work.
The idea of expense got my mind working so I calculated just what it would cost to fire form 100 cases. The cases were bought and paid for when the factory ammo was bought so they are a wash, the money has been spent and is just sitting wasted on a shelf for now. My pound of Unique was purchased several years ago so cost was about $27/7000 grains. Primers were also purchased several years ago for around $27/1000. Premium brand Cream of Wheat is about $2.54 for 28 ounces or around .02 cents/grain. Figuring 1300 grains of Unique, 100 primers and 2600 grains of COW (a fudge figure at 20 grains/case, it would probably be less), it would cost me $7.48 to fire form the cases. Gas to the range is a wash since I'd combine the fire forming with a normal range trip. But that makes $7.48 to get 100 usable cases vs. $58.14 for 100 new ones from Graf's (cost plus shipping); I'm seeing an advantage to fire forming. Based on previous experience fire forming new brass with COW and blowing out shoulders on new .250 Savage and 2X .243 brass (without annealing) to make AI cases the case loss should be 0.
Of course, if I can get the necks expanded with tools on hand that's free, but risk of case loss is greater. Like a certain form of sex, lube is the key...
This is why I like handloading, my left brained engineering mind is having fun with this.
