Your question is certainly valid,
pika, one that has crossed my mind a couple of times. Some manuals call the Remington ctg a rimless version of the .30-30, and tell us that identical loading data may be used. It is easy to infer that the same dies, with appropriate shellholder, might be used. Never having owned any rifle in .30 Remington, though, I never bothered to look it up.
I finally managed to locate dimensional drawings for both cartridges. The following information is from
Speer Manual for Reloading Ammunition Number 8 from 1970.
Body width, both at base and shoulder, is identical, which at first blush looks encouraging. Case
length is practically the same, too - - 2.040 for the .30-30, while the Rem is 1/100th longer.
The .30 Rem has a sharper
shoulder angle: 23 degrees as opposed to 15"39' for the .30-30. The base-to-shoulder distance is .077 shorter for the .30-30. I feel it might be impossible to make it work due to this. Even if you could get a cartridge loaded on .30-30 dies to chamber, the shallower shoulder angle would make for
VERY short case life - - Perhaps only one or two reloadings.
In short, I don't think it would be a worthwhile project in the long run. If someone
gave me an old rifle in .35 Rem, I might well experiment with the .30-30 dies which I already own. I'm certain that RCBS can furnish appropriate dies for the .30 Remington, but equally certain that they'd be fairly expensive.
Best of luck.
Johnny
LATE ADDITION: Trapper L beat me to it - - He posted while I was proof reading.
JPG