38/55 from 30-30
Must not be any old guys reading this forum...
Yes, you can fireform your brass to 38-55, but it's a bit of work. One way is to expand the the mouth of the case enough to take a .375 lead bullet, then fireform with a recommended full charge of a fairly fast-burning powder (maybe 4227 in this case) Downside is you will need to get a tapered expanding plug for your loading dies, which may cost more than the savings from using the 30-30 brass.
Another method, from the classic 'Cartridge Conversions' by George Nonte, needs nothing in equipment but powder and breakfast cereal.
- Prime your case
- Add a small charge of Bullseye powder
- Tamp a bit of tissue paper ontop the powder
- Fill the case almost to the top with Cream of Wheat or cornmeal
- Seal the case with a plug of bullet lube or paraffin wax
- Chamber and fire
The filler material lets the pressure build, and helps transmit it to the inside of the case before the whole works gets blown out the muzzle. According to Nonte, your 30-30 cases will come up about 0.08" short compared to factory 38-55, which makes no bother in a low pressure number like this one.
Nonte cites a charge of 10gr. of Bullseye to fireform .219 Zipper to Improved, or 16gr. to fireform 30-06 brass to Ackley. This is definitely a situation in which to start low and work up cautiously, since you can develop dangerous pressures with this type of load. I wouldn't use any slower or harder to ignite powder than Bullseye, you don't want the powder gasses to get outside the case while the pressures are still high, or you could collapse the case. Not dangerous, but messy.
Once you have your formed cases in hand, from my own experience I can recommend bullets in the 255 to 300gr. range, with an appropriate charge of a powder like IMR 4227 (see the Lyman Lead handbook), for a clean shooting and accurate load. Seat the bullets as far out as his gun permits, you want to get the bullet into the lands before things go boom. If you are punching paper, you don't need a lot of velocity, maybe 1,100 to 1,300 fps. Tune the load carefully to his gun, and minute-of-angle accuracy is not unreasonable.
Good luck, and have fun!