BEFORE TAKING ANY AIRGUN APART
1. Always make sure the gun is unloaded, uncocked and empty of air or gas (if applicable) before disassembly.
2. Never load or pressurize a gun until all the basic components are assembled.
These rules are to prevent accidental firing or ejection of parts at high velocity. This will happen when a component critical to containing pressure or tension is removed. Serious injury or death can result. This applies to the average hobbyist with limited tools and knowledge. For a professional, dealing with a loaded pressurized gun that won't fire is just part of the job. If you don't know how to handle a potentially dangerous problem, seek professional help.
SPRING AND GAS PISTON GUNS
Break-barrel guns, even when uncocked, have a spring or gas piston under powerful tension known as preload. Specialized tools are required to safely remove the spring or piston. Other types of spring-powered guns may have preloaded springs. Research and the necessary tools are recommended before attempting to work on these types of guns. Injury or death could result otherwise.