I hunt Eastern Ontario Whitetails (so NO dog-sized Bambi's) with a 40 cal.
With 60 grains of powder if produces about 200 foot pounds of retained energy out at 100. I won't shoot over 70 and between 35 and 50 yards would be my "comfort zone" (have to be serious, it's a 40 after all).
Have used this for the past 8 seasons. Haven't lost a deer shot with the 40 (4 of them) and each shot was a through and through.
Point is, a 45 cal ball over 40 or 50 grains of powder should be retaining 240/260 foot pounds (respectively) out at 100 yards - 20 to 30% MORE energy than my 40 - so if you keep the shots to a reasonable distance and only take a "standing still" broadside or quartering away shot with a perfect bead on the "boiler room", you would, in my opinion, have more than enough power to take down Bambi.
(2013 season, 40 cal, .395 ball, .018 pillow tick pre-lubed/wonder lube, 60 grains Goex FFF, 8 am, shot was 27 yards, ball went right through (post mortem showed it traveled through both lungs and nicked the heart on the way by) recovered in somewhat less than 100 yards)
(after I pulled the trigger I yelled from the stand "I shot you with a 54" - that caused him to lay down about 70 yards later :rotf: )