... and today you might add the .224 Valkyrie to that family tree!
Interesting question, and certainly not a dumb question. I own both so I just went out to the shop and pulled out a Marlin 30/30 and Winchester 30/30 and tried chambering a 30 Remington. Nope, not going to go -- the 30 Rem shoulder hits the 30/30 chamber shoulder area just early enough you cant force the bolt closed. The Marlin extractor does pull her out of there but not with a firm enough hold to eject. The Winchester extractor doesn't get a pull. The Marlin feeds 30 Rems from the magazine just fine. The Winchester jams because the cartridge stop uses the rim to keep the cartridge ahead from getting on the feed ramp with the cartridge ready to feed.
Other than the shoulder keeping you from chambering it there would be no danger in firing a 30 Rem in a 30/30 -- same bullet, same powder charge, same base diameter. Well, maybe the case would be a scosh too long also in a factory round. I Use the Lee zip trim for brass trimming and so my 30 Rem brass has all been trimmed to the 30/30 length, but looking at drawings it looks like 30 Rem is 2.050 long vs. 2.040 for 30/30.
Model 8 adapted by law enforcment early 1900s. Same ballistics as the 30-30 but rimless so it would feed in the Remington Model 8
BP | Bronze Point | IMR | Improved Military Rifle | PTD | Pointed |
BR | Bench Rest | M | Magnum | RN | Round Nose |
BT | Boat Tail | PL | Power-Lokt | SP | Soft Point |
C | Compressed Charge | PR | Primer | SPCL | Soft Point "Core-Lokt" |
HP | Hollow Point | PSPCL | Pointed Soft Point "Core Lokt" | C.O.L. | Cartridge Overall Length |
PSP | Pointed Soft Point | Spz | Spitzer Point | SBT | Spitzer Boat Tail |
LRN | Lead Round Nose | LWC | Lead Wad Cutter | LSWC | Lead Semi Wad Cutter |
GC | Gas Check |