Shells are metal mostly, just loading single bb, some are in full plastic, coming with front loaded and rear loaded two kinds, and the Casyopea shell series that load bb and gas in one shell.
Front loaded shell not necessary to be tuned and shoots straight, the fps is about 320-350 in 5? barrel. The rear loaded one, it?s about 20-30fps higher than front loaded, but needs to be tuned to make it accurate.
I don’t have a Casyopea system one, so no informations.
