I know where you are coming and I appreciate your opinion but this is not like knives. A knife (in the form of a sharpened rock) was probably first used as a tool rather than a weapon. Guns on the other hand were first invented as weapons and they remain such even if used primarily for hunting. It's a relatively modern notion to create a specialized hunting firearm, especially in America where historically the primary self defense weapon was also used for hunting. It's this modern notion of separating weapons (ie:military type rifles) and "hunting rifles" that allowed the whole "sporting purposes" rationale to be applied. This article completely bows to the notion that we can somehow separate out those evil military guns but still fondle grandpas Winchester 94 because it isn't a weapon it's just a hunting tool.
There are a lot of avid hunters that are union member Democrats that hate the 2nd amendment and would be thrilled if we could ban all "military weapons", including pistols, as long as they can shoot some ducks/doves/deer whatever. We need to fight against the sporting purposes rationale whenever we can while reminding these Fuds that their toys are going to be banned next.