Go for a walk in any city these days and check whats in the gutter. CO2 cartridges are all over my town. I made a dipper boring out the hole, cutting a nickle size hole in the side and then welded a cheap 12 inch screwdriver so it is 90 deg. to the cartridge and have used it for years. Everything from .30 to .70 and cost was under 3 bucks. Even use it on gang molds. Fox