Create a "lethality index" to set tax and registration costs for firearms in order to supply a market-based control.

A lethality index which takes into account features of any individual firearm's characteristics and assesses points.
Taxes and registration fees would then be based on the points accrued by the firearm.
Low points assessed for single shot, bolt action .22 caliber rifles.
High points for autoloading .223 or larger rifle cartridges.
High points for lethality featues, eg pistols, external magazines, lasers.
Each point has a dollar value that establishes the tax levied when the ownership of the weapon is transferred, including the initial purchase from new. It would also establish the annual registration fee.
Consumers could then decide how much lethality they were willing to buy.
Jurisdictions could also use the rating to exclude any weapon over a certain point value.