I'm pretty conservative on my shots- I keep it to 100 yards or less on deer-sized game, and always shoot at stationary animals (if the animal is running, it has "won the game" already). My Knight Bighorn is sighted dead-on at 100 yards. As for the cap, I use musket caps, and I have never had issues with "welding" to the nipple.
Good luck to you! Since you're an archer, perhaps you can try the same tactics that got you close to calm deer in the past.