King supports expanding background checks to most firearms transactions, with exceptions for transfers between family members, calling such a position "the single most effective step" that can be taken to keep guns out of the wrong hands. He supports limiting the size of magazines to 10 rounds, and to make purchasing a gun for someone not legally allowed to have one a federal crime. He does not support a ban on assault weapons, believing it will not work and that such a ban is not based on the functionality of the weapons, which are not relevantly different from the many hunting rifles owned by Maine residents. He noted that the vast majority of gun crimes are committed with handguns, not rifles.