I wonder how the .500/.460 S&W compares to a Marlin 1895 in .45-70.
A JM Marlin 1895 is a whole helluva lot cheaper than the Big Horn.
I rebarrelled a Rossi 92 in .460 S/W. The OEM barrel was .454C, but I was concerned about chamber support. The rebarrel is 2x on chamber support by my design. I also 5/8-24 TPI for my .45 Colt heavy subs (VERY VERY QUIET).
It will NOT cycle .460S/W, but it will "First Round" them... then wimpy old .454Cs if the .460 didn't get the job done out the gate.
Regarding the 1895... I also have one of those (threaded also). A FANTASTIC GUN. 1:16 IIRC so keep the subs under 550 grain IMHO. 405s fly very well.