Heizer Aerospace Technology Firearms is a new company with a modern take on an old idea. The new Double Tap pistol is an over-under double-barrel pistol for concealed carry. These unusual pistols, with exceptionally smooth triggers, will be available with an aluminum or titanium frame, with ported or unported barrels, chambered in 9 mm or .45 ACP. The barrels will be interchangeable for quick caliber conversions, and a compartment in the grip will hold two extra rounds of ammunition.