Roundball, I know that others may have had different results with the .40 on deer, but I'll relate 2 experiences I had with one on deer. First time was when I shot a doe at no more than 15 yards with her facing me. I was using a 70 gr. charge. I must have pulled off enough to miss the heart (I wasn't expecting her and it was a snap shot), but I did hit her in the chest area. She didn't even flinch and in fact walked past me close enough that I could have touched her with my barrel if I would've extended my arm out. I reloaded and waited then tracked the blood trail for a while and it petered out. The second time, I shot a doe at about 10 yards just behind the shoulder. This time she jumped a little then trotted down the hill and across a draw. She stopped about 75 yds away and watched as I reloaded. Then she turned and went out of sight. I saw the ball hit her and actually found a small plug of flesh on the ground where it exited. Anyway, after a reasonable time I went to tracking. Where she had stopped the first time I found a pool of blood over a foot in diameter. Another 100 yds farther on I found another. After that the blood drops got fewer and there were no more pools. I eventually lost her trail amongst a bunch of other deer tracks. I can't be sure about the first shot, but I know that the second should have put the deer on the ground. I decided then that I would never use a .40 for deer again. A 90 gr. ball just doesn't deliver enough shock. I know that it should and can damage a heart enough to kill one, but anyone who has killed a deer knows that they can do amazing things even with their heart blown apart in some cases. I killed a buck once with a Whitworth slug that weighed 560 grs. It blew the heart up as well as a lung and that deer ran over 100 yds before dying. I did later kill another buck with my .40, but that was after loading it with a 172 gr. .41 conical that had been hollowpointed with a ball screw. If it's legal to do so in your state, 2 balls might do the trick though I don't know how it will affect your accuracy. Guess you'll just have to try it. If I was ever to try to hunt deer again with a .40 roundball, I would probably limit myself to a head shot.