Will cap & ball guns kill? OH YEAH ! <img src=icon_smile_big.gif border=0 align=middle>
Check out what my son just did with my 1858 Remington .44cal:
http://community.webshots.com/photo/...4604iIZSuEYuYI
This hog was taken using 30gr of fffg Goex and a 180gr conical at a distance of about 7yds. The hog expired after about 15 seconds. I would expect a deer to last a little longer, so you now know kinda what to expect.
The Walker has a longer barrel & holds more powder so it will be more effective and have a longer range than my piece. Bow range (under 25yds) I think would be a good estimate for using the Walker - but be prepared for a long track, as the gun won't be dropping the animal in its tracks.....it just doesn't have the knockdown impact of cartridge weapons.
I would advise shooting it ALOT before considering hunting with it. This will help break it in and get you familiar with its little quirks. My Remington is not all that accurate (pie plate size groups at 10yds - with some 10's thrown in), so it's hard to say exactly how accurate the walker will be (better I'm sure). Once you fire it a bunch, you'll know if it is a "hunter" or not.