Take away the fully auto firing function of military rifles and there is no difference in killing an animal or killing a human with any weapon. What facilitates killing one will facilitate killing the other. There is no design or feature other than the fully auto function that makes a rifle essentially more suitable for military action than for other purposes.
A gun used for self-defense is typically used in the home, and a rifle is not generally considered to be the weapon of choice in that situation. Most rifles are owned and used for sport, or just as collectibles.
America's rifle
"The AR-15 was developed in the late 1950s as a civilian weapon by Eugene Stoner, a former Marine working for small California startup called ArmaLite (which is where the AR comes from). The gun, revolutionary for its light weight, easy care and adaptability with additional components, entered the mainstream in the mid-1960s, after Colt bought the patent and developed an automatic-fire version for troops in Vietnam, called the M16.
With encouragement from the gun industry, the AR-15 grew popular not only among people who enjoyed owning the latest tactical gear, but also among recreational and competitive target shooters, and hunters. Many saw it as a pinnacle of firearms engineering ā ergonomic, accurate, reliable.
āItās kind of the standard, de-facto rifle now,ā said Evan Daire, 23, a gun-range worker in New Jersey who aspires to become a professional target shooter. āNo matter what role youāre looking at, it pretty much fills that role.ā "