About ~25yrs ago there was heavy discussion about every manufacturer trying to adapt their existing levergun designs to the .454 cartridge, along with a multitude of gunsmiths. The Freedom Arms guys were present, along with John Taffin, Mic McPherson and others. Ruger had just started building the SRH in .454 and a lot of folks wanted a companion levergun. None survived at 65,000psi, let alone the +90,000psi proof loads. The problem with the Winchester 94 is not just the rear lockup but the angle of the locking lugs. Because they're not vertical like the 1886/1892, they basically gradually splayed the receiver apart. Even the fatbody Big Bore version. Gunsmith Keith Dehart offered a conversion of the Big Bore 94 to .454 but pressures had to be kept around 50,000psi. None of the Marlin actions fared any better. The only action that would live with the .454 was the 1886 but it's obvious that there'd be no point in that. That's why the Big Horn Armory leverguns are basically a hybrid 1886/1892 action. Falling between the two in size.