Why are some primers colored while others are not?

There’s been a number of interesting questions posed to us by our customers regarding the appearance of centerfire cartridges they’ve bought from us. A couple of them have been in regard to noticing a colored ring that can sometimes be visible around the top and bottom of the case on certain brands of ammunition. Mostly, they want to know what its for and what does it do. We simply tell them it’s sealant and normal for some manufacturers to include it. The why part of the question however requires more of an explanation.

What are sealed primers and what do they do?

Primer sealant is typically a lacquer-like compound that is applied over the primer to form a watertight seal. This same treatment is sometimes applied to the bullet as well to give a complete seal all around. The idea is to prevent moisture and humidity which, given enough time, can degrade the powder charge inside. This in turn would eventually render the bullet inert. Not a good situation to be in if you’re out plinking with friends, competing in a match or if your life is in danger. You’ll likely notice it comes in different colors, such as red, purple, blue, green etc.

Why would I want a sealed primer?

For the same reasons listed above, it helps ensure the cartridge is protected against the elements. If you’re in law enforcement or the military, this means being outdoors for extended periods of time in different weather conditions. Day after day, month after month. You need some kind of guarantee the ammo you carry will work when you need it. The same thought process applies for outdoorsman and hunters too. For the average person, this could mean an added layer of ammo durability when it comes to personal defense. Such as for someone who regularly conceal carries, your ammo is exposed to sweat and changes in temperature which can be hard on ammunition. Lastly, if your stockpiling ammo, it helps to have it in order to ensure long term storage of your ammunition.

Do I need sealed primers?

It depends. Most range ammo or training ammo doesn’t really need it since its expected that it will be used relatively quickly after manufacture and purchase. There isn’t a performance difference between sealed or unsealed ammo that is in good condition. Even without sealant, most manufacturers guarantee a minimum shelf life of 10 years. This is assuming the ammo is kept in its packaging in some kind of air-conditioned environment. Ammo that doesn’t have sealant also tends cost a bit less since its one less step in the production process. However, ammo that has sealant is always nice to have due to the aforementioned qualities listed above. If you’re concerned about long term storage or long-term durability, it may be the preferred choice.

The bottom line:

Unless you have a very specific reason for wanting it, such as long-term storage or self-defense, sealant isn’t required for general target practice and training ammo. Proper ammo storage stands be a more important issue for most of us, and is relatively simple and easy to do. Likewise, if you happen to have a decent stockpile, it helps to rotate your supply from time to time to ensure its ready for use. A basic check of the top and bottom of your ammo will let you know if its sealed or not. If you’re still not sure, some manufacturers may list their specs on the company website as well.