Both of these markers are early Sheridan pump/bolt "rifles". The top is a KP3-- a pump, while the explosion diagram is for a K2 boltaction.
Both models were primarys for modern milsim paintball. they offered a great alternative to early mechanical models like the Nelsplat and Tippman 68.
They fire traditional .68 cal paintballs, but use feed carriages (on the NP3 a tube along the top and a tube down the side on the K2) rather than a traditional gravity feed hopper.
Both markers are considered "stock class." That is-- both markers only fire one round as per loaded on the chamber manually. At the same time, they are limited to a specific number-- most commonly 10.The most important factor is limited air-- while most stock class are limited to 12gram cartridges, some, such as the KP3, could manage Co2 tanks from 4oz. up to 20oz.
Modern components, replacing old rubber cupseals or brass stoppers, include polymers such as delrin.
If you want a vision of the future, imagine a boot stamping a human face...forever" ~George Orwell