Safe handling, firearm mechanics, ammunition and cleaning
The handling rules
Treat every firearm as loaded; keep the muzzle pointed in a safe direction; keep the finger off the trigger until the sights are on the target and you intend to fire; know your target and what lies behind it. Add eye and ear protection, and never handle a firearm when intoxicated, exhausted or distracted.
Mechanics you must know
Identify the barrel, chamber, action, magazine, extractor, ejector and safety. Know the difference between double- and single-action revolvers and between the cycling of a pistol and the manual operation of a bolt-action rifle. Understand calibre and cartridge designation, and that a firearm must only be fed ammunition matching the markings on the barrel and the chamber. Headspace faults, an obstructed bore and a squib load (a bullet lodged in the barrel) are catastrophic: stop, unload and clear. Misfire drill: keep the muzzle in a safe direction, wait about 30 seconds in case of a hangfire, then eject and inspect the cartridge.
Ammunition
Components are case, primer, propellant and bullet. Ammunition deteriorates with corrosion, oil contamination and poor storage; never mix ammunition types and never fire reloads of unknown origin. Possessing components is possessing ammunition.
Cleaning
Unload and remove the magazine, verify the chamber is empty, strip as the manual directs, clean the bore with a brush and solvent from the chamber end, run patches until clean, apply a light film of oil, reassemble and function-test. Excess oil attracts grit and can cause misfires. Always check the bore is unobstructed before firing.
Traps
Confusing calibre with cartridge name; ignoring the 30-second misfire wait; assuming a 'click' means an empty chamber; cleaning a firearm that has not been verified unloaded.