CH 4D, Environment Test might be able to supply the dies, that's where I got mine. They were also quite a bit cheaper than anyone else. All of my 25-36 brass is made from resized 32-40 donor brass. I was fortunate to have a good supply to start with. Resizing is a breeze with the CH 4D FL sizing die. I anneal the case necks first, then I just spray on a little lube on the brass and with one moderate stroke I have my 25-36 brass. Length is also correct when using 32-40 brass. I would strongly recommend using 32-40, which is the real parent case, .30-30 was for the 25-35. Of course, YMMV. Good luck, my 25-36 is probably the most accurate of all my old Marlins, and is a pleasure to shoot.