Abstract: A powerhead mounting bracket is connected to a diver's breathing tank support. A cord connected to the receiver has a plug with a projection for loosely fitting in an axial bore of the powerhead. The plug is placed in the axial bore and the powerhead shaft is placed between the flanges on the receiver. The sling at the other end of the powerhead is stretched, forcing the powerhead tight against the plug, and the stretched spring is hooked into slots in the receiver. The stretched sling holds the shaft of the powerhead against the base of the receiver and holds the powerhead longitudinally against the plug. When required for use, the powerhead shaft is grasped near the firing end and is pushed in a direction towards the sling, further stretching the sling. When the plug drops out of the axial bore, the shaft is pulled outward from the receiver, allowing the sling to become untensioned, whereupon the sling drops out of the slot in the receiver.

Abstract: A 30-30 casing has sharpened rings formed in its enlarged base. Powder is packed in the casing, and it is sealed by inserting a primer portion, which is a 38 caliber pistol shell with a primer, in the open end of the packed casing and compressing the edge of the casing in the base area of the primer portion.Radial extensions on the casing hold the cartridge centered in a barrel spaced from a firing pin.The primer is ignited by hitting the sharpened rings against an underwater object and thus driving the cartridge and primer rearward against a fixed firing pin. The casing rockets forward out of the barrel, leaving the primer piece and smashing into the underwater object while the powder burns.