The Callahan Full-bore Auto-lock was a weapon with armor-piercing capabilities. Jayne Cobb owned one of these weapons and named it "Vera". It was reputed to be Jayne's favorite gun, though it is rarely seen and, strangely, it is not one of the weapons he takes to defend himself at the end of Serenity, instead preferring to use his assault rifle Lux against the Reavers. Although not obvious, its name seemed to indicate that the weapon can dynamically switch bore sizes depending on the cartridge size that the user desires. The weapon required oxygen around it to operate.