Abstract: The invention is a pin valve having a detachable valve body cover which makes the valve stem assembly accessible from the end of the valve in which the valve stem protrudes. The removable valve body cover can be replaced independently if this end of the valve is damaged. The valve body cover also has a valve seat which is more accessible and is more easily machined. The valve body cover is typically adapted to accommodate an allen wrench type tool to simplify removal and reattachment. The invention eliminates the need to disconnect the valve at the second open end when replacing the valve stem assembly.

Abstract: A combination including a paint ball gun with a gun barrel has both a muzzle portion and at least two interchangeable compression zone portions of slightly differing diameters. The compression zone portions are preferably attachable and deattachable from the muzzle portion by a non-threaded connection mechanism, such as by a snap-on type connection mechanism, a cam-lock type connection mechanism or a bayonet connection mechanism. The invention allows the user of a paint ball gun to select a compression zone portion which is most optimally matched to the diameter of the paint ball ammunition to be used in the paint ball gun. The invention thereby optimizes paint ball gun performance.