Targo? Anyway, creating one has been on my mind for a long time. Maybe 20yrs ago I picked up something like 3 or 4 BRICKS of .22R shot cartridges for stupid cheap,.....like around ten bucks a brick. Have had the idea of a smoothbore in the back of my mind since that day. Semi-auto would be nice since shooting down flying bugs was my goal(think dragonfly)but I've gotten soft and don't really wanna blast the little critters anymore. Still, semi I think could work with a much lightened bolt. Have a spare 10/22 bolt I tried to work on but harder than,.....well, harder than anything I can think of at the moment. Would require grinding and/or tooling better than I have available. Remington M24 is another spare bolt I picked up for the same project but coming up with a barrel to smooth out would be more difficult. Have half a dozen Ruger barrels I'd smooth.
Another option nearly as good would be a pump. Have a halfway decent Winchester 61 but boring that barrel out would be a crime. Recently picked up a trashy Remington M12 for cheap and that bore is already gone so all it needs is a cleanup and a cord run through the barrel with some valve grinding compound. (kinda wanted a pumper without a disconnector ala Colt or older Marlin, but why I don't really know)