The newest .410 3" slugs weigh 115 grains and run about 1,400 - 1,600 fps. They are of soft lead and combined with the punkin' ball shape will not penetrate well. I would expect performance to be less than the .30 Carbine which has a jacketed bullet of 110 grains at 1,900 fps. Neither would be my choice for a charge stopper or protection, though lions are reported to not be real tough like a large bear. Could it kill a lion under perfect conditions? Sure, but that being a single shot, ya better be accurate with that dinky little slug. Otherwise, you've made a mess to clean up.