Straight from the Shooting Dictionary: Make sure to listen for shots that do not sound right.
It's always worth brushing up on possible malfunctions that can occur, and doing the right, safe thing in response.
If your shots do not sound right, you may have run into one of these culprits.
Squib: a fired projectile does not have enough force behind it to exit the barrel, and thus becomes stuck.
Squibs are cartridges that fire with very little power and may possibly wedge a bullet in your barrel. It is extremely important that if you hear a low thud instead of your normal bang, unload the gun and check your barrel for obstructions.
If you have a bullet stuck in the barrel and fire another bullet into the captive bullet, your barrel may explode. This is nothing to mess with; address it immediately, and don't take another shot until you're 100% you've cleared it.
Misfire: a cartridge that does not discharge or that only partially discharges.
A misfire can be a cartridge that does not go off when shot. The culprit of a misfired cartridge may be faulty priming, old propellant, or wet propellant, but can happen on cheaper promotional or commercially loaded ammunition too. It's otherwise known as a dud.
Again, unload the dud, and be 100% clear before reloading and firing.
Hangfire: an unexpected delay between the triggering of a firearm and the ignition of the propellant.
A hangfire is a very dangerous situation, as a cartridge has misfired and it may ignite at any moment. I personally have never dealt with a hangfire (luckily), but I approach every misfire like it could be one.
If the cartridge fails to ignite and fire, count to 30 before opening the action and removing the misfired cartridge. If you do not do this step, a cartridge could possibly go off.
Be careful and make sure to count to 30 first.
Listen to each shot when you fire your firearms, and these three gremlins will be able to be addressed before they can become a serious problem.