I have seen moose harvested with just about every caliber one could think of and a few harvested inadvertently with 50 and 20/25/30 MM class weapons. Moose are relatively easy to kill, much like buffalo/bison...BUT! a less than perfect shot, which would result in a relatively quick kill on most any other game animal, may result in you having to swim or wade out into a bog/lake/pond to recover it. Given that we hunt along or in any of the aforementioned the people I hunt with have adopted a break the shoulder first to anchor the animal, the loss of meat is minimal in the overall scheme of the hunt, but not having to get up to your neck in cold brackish, ice covered bog or open lake water ...."PRICELESS" Calibers I have used and would use again..Kissing distance out to 300 yards. 6.5x55S I have used both 156 RN and 140 Spitzer to equal effect 30/30 150 or 170 gr bullets, though a friend has developed a 200 gr Cast bullet load 308 Win 180 std cup and core or premium 7.62x54R 180 or 200 grain bullet 30/06 usually 180 std cup and core or premium bullet 12.4x44R 361 gr PP bullet Hard alloy and a Hodgdon 350 gr RollingBlock 45/70 Marlin 1895 Cowboy model Have used 300 gr Partitions (discontinued) loaded to 2300 fps as well as 405 JSP at std load 330 PP Gould bullet at BP velocities and 5-700 gr Postell/Schmitzer out of Rolling Block/Sharps 300 Win mag a 180 can be used but a well constructed 200 is a better choice 375 H&H I have used Speer 235 SP with great effect, but a 270-300 gr bullet is a better choice if shoulder busting is your preferred method of anchoring a moose. 416 Rigby 400 gr at 2400 fps any quality bullet made will work especially for shoulder busting or end to end shooting. .451/.457/.54/.577/58 Caliber Enfiedl/Zouave style Muzzle loaders 530 -900 gr Minnie or Solid bullet, 200 yds or less, will definitely stop them in it's tracks. 11.15x60R (43 Mauser) 370 PP Pure lead 71/84 mauser .577 Snider 480 gr Hard cast PP bullet breaks shoulders quite well 12 Gauge Brenneke/Sabot/Shuttlecock/Paradox Slugs 1 ounce or better loaded at max Dram equivalents, smokeless or BP. Of course this is based on my hunting experience. I have used rounds for culling operations that are either not suitable or legal for hunting, so have not listed them.