We get it. What would you suggest?
Make the cost of bullets start at $250/bullet. You can have all the guns you want, but you will think twice about firing a month's salary worth of bullets in a shootout. Most of these broke sociopaths committing mass shootings would not be able to buy more than a few bullets at a time.
Force gun manufacturers to make all of their guns traceable - be it by unremovable serial number, fingerprint identification, or some such other technological mechanism. ALL guns should be able to be traced back to their original purchaser. Or perhaps ALL BULLETS should be traceable - one of you geniuses can sort that out. That initial buyer GOES TO JAIL FOR ANY CRIME COMMITTED with his/her gun (or his/her bullets), unless he can substantiate the sale of the gun to another individual, pawn shop, or whomever. If the gun cannot be traced back to a specific person,
the gun manufacturer must pay out in civil court to any victim shot by one of their products.