What Size Of Primers are Used For 9mm?


Primers come in a variety of different sizes, with each primer varying in size slightly between each manufacturer.

9mm rounds are some of the most common rounds used for both target shooting and self-defense. The 9mm pistol has become one of the most popular handguns, thus, 9mm primers are in high demand.

In recent years there has been an extreme shortage of 9mm pistol primers to the point they were basically unavailable. As a result, it forced people to ask the question of whether other primers could be used for 9mm reloads.

What Caused This Shortage Of 9mm Primers?

There are two main factors that have influenced the primer shortage that we have experienced over the last few years. The two factors are an increase in demand for primers and disruption to normal manufacturing.Because of COVID-19 and other political concerns, more people bought guns than ever before, and those that already had guns then wanted to stockpile ammo in the face of uncertainty. As a result, supplies got bought up very quickly. On top of that, all the health and geopolitical complications made shipping and imports trickier than they have been for a long time, which influenced not only the importing of manufactured ammunition but some of the critical ingredients required to make the ammunition.

Who Makes 9mm Primers?

9mm primers are made by the four main ammunition makers:

  • CCI
  • Federal
  • Winchester; and
  • Remington

Remington has had significant issues as a company in the last few years, so they had to close down operations for a period of time, and even when operating, were operating under capacity.

There are some overseas imports as well, but the four US makers are the main suppliers.

But after being recently bought out by another company, they are on their way back to full productivity.

9mm Primer Types

In general, there are two sizes of primer: large and small.In the case of a 9mm, you will be working with the ‘small’ primers. These are typically used to support rounds for 9mm, 38 special, and 357 magnum guns.

Within this ‘small’ group there are four main types of 9mm primer:

  • Small Pistol
  • Small Pistol Multi-Purpose (regular or magnum)
  • Small Pistol Magnum
  • Small Rifle

For many, a small pistol primer, or small pistol multi-purpose primer will be adequate. A small pistol primer measures approximately 0.175” in diameter.

You can view and buy a range of 9mm primers at thecastlearms.com.

The main difference between the three 9mm primer types is the thickness of the cup on the primer. Though there are some other subtle differences, the cup thickness is the critical difference.

The reason cup thickness matters is that if the hammer in your weapon doesn’t apply enough pressure to the cup, the round will not discharge (this is a ‘light strike’).

The small pistol 9mm round has the thinnest cup, followed by the small pistol multi-purpose, followed by the small pistol magnum round, followed by the small rifle round.

You should always use the recommended primer type for your pistol, but in the event you are unable to obtain any of the regular primers, you could potentially use magnum primer or small rifle primers.

However, if your pistol has a super light spring, then you run the risk of light strikes as you try the thicker (magnum and small rifle) cup.

Most guns out of the box will not have this issue and will have no issue with the magnum or small rifle cup, but if you have a modified weapon or something with a light spring, you might get light strikes.

If you are going to substitute a magnum pistol primer, or small rifle primer you should reduce the amount of charge in your round. Reducing the amount of charge by 10% is a common rule of thumb.

9mm Primer FAQs

Can I Use 9mm Magnum Primers Instead Of 9mm?

Many people have successfully used magnum primers instead of standard primers, though this is not recommended if you have the choice. If you want the best of both worlds then you should consider using a multi-purpose primer.

Is It Safe To Use Small Rifle 9mm Primers In My Pistol?

You should always use the recommended primers when reloading rounds for your pistol. However, if you are unable to get the recommended primers, then many people have successfully used small rifle primers in their pistol rounds.

Will My Pistol Reliably Discharge A 9mm Rifle Primer?

Everyone will recommend sticking with the recommended primer for your pistol, but if you are unable to get standard 9mm primers and need to use your gun, there are many examples of people successfully using small rifle primers in their pistol without issue. If you have modified your pistol with a lighter spring then you could have issues with light strikes, but if you are using a pistol with standard configuration then you should have no issues.

Can I Use Magnum Pistol Primers Instead Of Regular Pistol Primers?

Most reloading manuals and books say no, but many individuals have tested and documented the difference and cannot measure a difference in velocity or any increase in light strikes.

Will The Small Rifle Primers Give More Kickback?

If you are a sports shooter, you might be worried about the kickback of using a thicker primer and whether this will disrupt your aim ability to recover and aim for the next shot.

Extensive testing between the three different types of primer shows there is no difference in velocity, between the three different primers types.

The main consideration for you as a shooter should be whether your gun is adjusted to apply enough pressure and reduce the chance of light strikes. If your gun has the standard configuration and has not been adjusted or optimized for competition, then you should have no issues utilizing other primer types.


Primer Storage

If you are lucky enough to have a good supply of primers during this time of worldwide shortage, ensure you store them safely.Like good ammunition storage practices, your primers are even more delicate and should be kept in a cool and dark place, away from heat and gunpowder.

It can be tempting to take them out of their box and put them in some other container to be more efficient with space, e.g. a jar. Please do not attempt this.

You significantly increase your likelihood of an incident. If you drop a primer and it lands the wrong way it could detonate and lead to a chain detonation of other nearby primers and cause significant damage to the surrounding area, and to you as a person.

Leave them in their box, and places multiple boxes inside a waterproof storage container.

Final Thoughts

If you want to shoot a ton of 9mm Ammunition, just buy the rounds direct and stop worrying about chasing primers. The value of 9mm is truly that the ammunition is cheap enough to purchase and utilize for training and day to day to day use.

There are a variety of 9mm primers available for purchase, though supplies of certain primers have been severely restricted in recent years.

You should always use the recommended primer for your weapon when it is available, but if the recommended primer is not available then there is the opportunity to use another primer in your rounds.All reloading manuals will staunchly oppose this, as will manufacturers. But many people have used primers interchangeably without any notable change to velocity or increase in light strikes.

Always exercise care and caution if ever going outside of the recommendations when it comes to ammunition composition, and only do it as a last resort. But it is possible to use alternative 9mm primers, especially for a regular pistol, if the situation demands it.

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