If I was restricted to one cartridge, as long as I could handload it would be the original 300 Win. Mag. I shot one for the better part of 15 years, more for fun and education at distances out to 1000 yards. I killed a little game with one but it's a bit overkill for anything under 200 lbs. and by the time I was living in elk country I was head over heels in love with a Shiloh Sharps in 45-90.