The majority of spring guns are loaded by pushing a pellet into the exposed breech, whether its a break-barrel, side lever or under lever. There are however a couple designs that don't expose your fingers to this problem. The most common is the rotary tap. Its generally found on better quality airguns as it requires fine tolerances to work right. Its basically a section of the barrel that rotates 90 degrees so a pellet can be dropped in from above. When the tap is rotated back the pellet is in line with the bore.
Theres also a design that has a trap door breech, where you flip up a small door to expose a loading tray. A pellet is dropped into the tray and the door is closed, sealing the chamber.
There are also a few spring guns that have a magazine, usually a rotary design like a revolver, that indexes the next pellet when the gun is cocked.[/img]