Seriously, the only kind of targets you would want to use this weapon on are the kind that are protected by bulletproof glass or armor. And in order to do that you will need to be within 500 yards at the most, if not 300, and you will have to ambush them.
An animated instructional video from WW2 indicated that german tank armor near the end of the war required soldiers wielding the Boys’ .55cal anti-tank rifle be within 300 yards of their target, downgraded from the original 500 yards. Lightly armored vehicles of our modern age are as tough as a full size ww2 german tank, or better in some cases.
I guess you could use it to shoot a Moose, you cant get this close to Moose before they bolt, and it takes this kind of firepower to knock down a moose. It would be a good gun against a Bear too as long as you can get at least 100 yards of warning on it.