NcSTAR has you covered with Hard to Find Cartridge Laser Bore Sighter sizes. Introducing the .50 BMG Caliber (TLZ50) 12 Gauge (TLZ12G) and 20 Gauge (TLZ20G) Cartridge Laser Bore Sighters. The 12 Gauge and 20 Gauge Bore Sighters are perfect for Slug Hunters while the .50 BMG Bore Sighter will get you on paper without wasting that expensive ammo. These Cartridge Laser Bore Sighters are Self Contained and Ready to use with no other accessories needed.