IsoTac Airsoft talk about their .209 Primer Conversion For ThunderStrike V2 for use in airsoft... "This is our .209 Primer Conversion for the ThunderStirke V2. It converts the airsoft grenade from using 8-shot ring caps to .209 Shotgun/Muzzleloading primers, making it slightly louder. Although we still use and recommend 8-shot ring caps, primers can have many good uses."