If you own a side-by-side or over-under shotgun, chances are you have all that great gear to go with it — the nice case, attractive apparel, cleaning stuff and maybe a really cool pair of shooting glasses. Now what about those snap caps?

For break-open shotguns, snap caps were designed to relieve the tension in the trigger springs within the action while storing the gun. Snap caps are shaped exactly like a shotgun shell, and some people refer to them as dummies.

You drop the snap caps into the breech, close it, then pull the triggers uncocking the internal hammers and relaxing the mechanism. In fact, you can purchase snap caps in all gauges.

Most people store their shotguns with internal hammers cocked (trigger not pulled after the gun is closed) or uncocked (triggers pulled without any snap caps). Either way, the coil springs inside the triggers suffer from too much stress with the potential to impact reliability.

The snap caps are typically made of aluminum, steel, brass or plastic. Prices range from about $9 per pair to $20, usually depending on the material. To help prolong the life of your shotgun, snap caps become a relatively cheap investment.

Aluminum snap caps (left) tend to be the best alternative in terms of price and durability. Plastic snap caps (right) tend to be less expensive than metal versions. Here you can see the interior spring that helps regulate the pressure of the firing pin.

But snap caps become important in other ways for shotgun enthusiasts, although the end game is still the same.

For example, in the shotgunning sports there's a practice exercise called the "flashlight drill." It involves dropping a small Maglite flashlight into the muzzle of your shotgun (or a specialized bore light).

You mount the gun to your shoulder and swing to an imaginary target that's flying along the seam of your ceiling and wall and finally pull the trigger. The purpose is to build so-called muscle memory for actually shooting at real-world targets and to help cure a flinch.

Without snap caps, pulling the trigger exerts undue stress on the firing pin and trigger. Over time, you're potentially looking at broken firing pins and trigger springs that need to be replaced. The price of snap caps pales in comparison to those kinds of repairs.

For older shotguns, in particular, you should definitely purchase a pair of snap caps that have cotton "mops" on the end of them. The mops are like big Q-tips that you spray with gun oil. Inserting the snap caps into the gun helps absorb moisture and keep the bores lubricated against rust.

These snap caps feature cotton "mops" that should be sprayed with gun lubricant to help prevent rust in the bore of the shotgun barrel.

Make sure you have the correct gauge snap cap for your shotgun. Just like with shotgun shells, you don't want to accidentally drop a 20-gauge load into a 12-gauge chamber.

Don't try to save a few bucks by substituting a spent shotgun shell with a snap cap. The more you pull the trigger on an already-fired primer, the deeper the primer gets to the extent that a very recessed primer no longer serves the purpose of exerting sufficient resistance against the firing pin.

Even though you have snap caps in your shotgun, you must always treat your firearm as if it is loaded, including the cardinal rule of never pointing it at anyone. It only takes a single mistake to think that you have your snap caps inserted and tragically find out there was live ammo in the shotgun.

Snap caps are a cheap way to prolong the life your shotgun and help ensure its reliability in the field. After all, when a game bird flushes and you pull the trigger, you want your shotgun to go bang.