if i still had access to a lathe i'd build one. this is for a rifle i gave my grandson a few years ago. we were plinking saturday & with that high capacity clip the CO2 went pretty quick. it's not that big a deal. i'll keep my eyes on the classifieds & see if one turns up so long as the hammerli cartridges will work. i haven't looked but i've not seen the crosman bulk cartridges in a while. i'm on my last crosman cartridge in my hammerli!! unfortunately he left this rifle at his grandma's ( my ex ) & it must have been put away wet as there is some pitting on a small area of the barrel. i explained to him the value of proper maintenance & think he got the message. this is a discontinued 1077 W. the other grandson that got one of these is a hard core hunter & knows how to care for his guns.