RE: velocity.....
Although the numbers might look bad Mauser06.. remember roundballs have been killing deer and other big game for a long time and at some incredible distances. I think the shape of the roundball helps in the penetration also. Once they poke through the hide, there is no telling where that devil will go.
I've had roundball pass through deer all the way out to 80 yards so I would not be too worried about the numbers. I would worry more about shot placement. You put a half inch hole through a vital organ like the heart or lungs, and something is in for a bad day. Also as others will tell you, the internal damage the roundball does will astound most people. I've seen them turn to mush internal organs.
Just place your shot, and let the roundball do the rest. You will be getting and eatingdeer.