What is an assault weapon? Competing and sometimes mutually exclusive answers to that question seem to be driving a lot of debate and misunderstanding between gun control advocates and gun enthusiasts. Discussions about this can often end up being dismissed as a fight about what a gun looks like or how a gun labeled as an assault weapon is really just the same as other guns that share its caliber if not its design. I think that kind of thinking is missing a bigger picture.
So here is how I draw a distinction between assault weapons and sporting guns, an assault weapon is a gun designed to be a modern weapon of war or is directly derived from a modern weapon of war and therefore shares a significant number of parts with current military weapons. It isn't the magazine capacity, caliber, or shape that makes an assault weapon different from a sporting gun. It isn't judging a gun by some sort of checklist of features that if it has too many of them, it then gets an assault weapon label. The answer to me is in why it was designed, for what original purpose, and its relationship to military weapons that should matter.
A hunting or sporting rifle might have the same caliber as a current military rifle, but the hunting gun has a very different evolution of design. It cannot be remade with the replacement of a few parts into modern military assault rifle. Whereas an assault weapon like an AR15 is in almost every way, exactly the same as a front line, modern, military rifle, except that it cannot fire fully automatically without replacing a few small parts inside the action. It is the similarity of design, capability, and the sharing of parts with the military versions that makes such a gun an assault weapon.
I personally own a rifle that fires the same ammunition as the main assault rifle of the US military, 5.56mm or .223 caliber. My rifle shares nothing else in common with the Army's M4 carbine. Mine is a bolt action rifle that requires the action be manually operated between shots to eject a spent case and chamber a fresh round. It cannot fire in a fully automatic way. It cannot even fire in a semiautomatic way. I cannot possibly use it to spray 30 or more bullets in just a few seconds or hundreds of bullets in a minute or so. Because my rifle was never designed to put out that kind of firepower or to kill dozens of people in a few seconds, the M16, AR15, and M4 were and can. So, I'm not bothered by restricting their use to the military, along with many other powerful, deadly weapons of war.