Never shot a rifle caliber repeating rifle match huh? Lots of levers shoot rifle caliber cartridges in the appropriate category. I shoot a Winchester 1894 in .38-55 as did a few other folks at the SER, one fella shot a .45-70.
All your arguing and scientific noodling aside the rules are clear: “Rifle Caliber” competition rifles must use traditional, period, rimmed cartridges. No cartridge chambered for use in any SASS approved main match revolver or rifle may be used in the “Rifle Caliber” competition, except the .56-50. Thus, .30-30 (.30 WCF), .38-55 Marlin & Ballard, .43 Spanish, or .45-70 Government cartridges are legal, while a .375 Winchester, .444 Marlin, .32-20, or .44-40 are not legal. Shotguns using slugs are not allowed in the Buffalo Single Shot competition. "
.44-40 by definition is a pistol caliber cartridge and there are categories specifically for pistol caliber rifles. Action throw length and recoil difference would allow a pistol caliber rifle an unfair advantage over the rifle caliber rifle thus different categories. You are however free to run a match with pistol caliber rifles out to any distance you like since nothing in the rules defines the distances to be shot just the categories, gun and ammo requirements.
PS- using jacketed bullet data to argue with is pointless for SASS. Lead, gas checked lead or polymer coated lead bullets only.