The Canon Knock Gun is a powerfull canon the same as the Knock Gun and you can take
when you finish the game 100% at shotguns.
To beat the game 100% you must do all the wanted posters,all hunting,buy everything,
do all pony express,beat all poker tournament and do all rancher's. In other words, you must beat all main and side missions.

omg the weapon is so power full if you want to get it beat the game

ohhhhh wee must get 100% too get cannon gun i dont understant what is knock gun and cnnon
knock gun lol

dude it is necesary find all of golds???

it is a gun to be put in your shotgun slot when you finish the story