Basics of Priming Brass Ammo

by Bob Shell
Priming ammo is easy and with the right tools it can also be a fun family effort.

3 stages of priming old primer, decapped & primed
3 stages of priming (from left to right) primed, decapped & an old spent primer.
Bob Shell
Bob Shell

Apache Junction, AZ -( The following is a basic primer on reloading Primers and some tips on re-priming ammo brass cases.

Picking up after you inspect and clean your cases, the next step is usually depriming and sizing the case.

It is necessary to remove the used primer in order to produce new ammo.

While depriming and priming are mechanically simple, there are some difficulties in priming the case more so then people realize.


There are two main sizes of primers large and small. Further, there are rifle and handgun primers and it is important to use the correct ones. Then there are standard and magnum primers and some other things to consider. As a rule, rifle primers have a thicker cup because they have a stronger firing pin and they operate at a higher pressure. In addition, a rifle primer is slightly taller then Handgun Primers so it would be difficult to seat a rifle primer in a handgun case without it sticking out.

Single stage reloading press set up for rifle primers.
Single stage reloading press set up for rifle primers.

Primer Cautions

There are many reasons not to use the wrong primer. A rifle primer has a different formula then the handgun type because it ignites more powder over a longer period of time. Like any reloading chore, priming must be done correctly in order to have safe and reliable ammo. Besides box primers there are other primer types such as Berdan, rimfire, and pinfire but their explanations are for another time. One thing is if you are reloading foreign cases especially military, they may have Berdan primers. (Read More on Corrosive Ammo with Berdan Primers.)

Military case with Berdan primer note it is larger then a Boxer primer
A Military case with Berdan primer, note it is larger then a Boxer primer.

While it is possible to reload Berdan primers, it takes special tools and primers to accomplish that and for the most part isn’t worth the trouble. They have two holes offset instead of the center hole of a Boxer primer and frequently they are a different size.

The Berdan priming system has 2 holes as opposed to the 1 hold of the Boxer type
The Berdan priming system has 2 holes as opposed to the 1 hold of the Boxer type (Top)

Primer Case Prep

While not always necessary, cleaning the primer pocket is a good idea. After a few firings residue can build up in the pocket making it more difficult to seat a primer. All you need is a very inexpensive tool, like the Lyman Primer Pocket Cleaner or proper size screwdriver and a pocket can be cleaned very rapidly. If you shoot black powder cartridges then the primer pocket should always be cleaned as well as the rest of the case. Black powder produces a lot of residue, which must be dealt with after each firing.

A high primer is a very common mistake and can easily be avoided
A high primer (right) is a very common mistake and can easily be avoided

Priming must be done correctly in order to have good ammo. The biggest mistake I see is primers that are not fully seated. Such ammo will cause various problems and can easily be avoided. A high primer in a revolver will not allow the cylinder to revolve as it is caught on the recoil shield. High primers can cause misfires and inconsistent ignition and misfires and hangfires. In a tubular magazine, there is the possibility that a high primer can go off in the magazine causing a chain fire. A slam fire is also a possibility in a semi auto gun.

Since priming is so simple all of these issues can be avoided by taking time to inspect your ammo.

A primer should be seated from .001 to .002 below the case head. If you have a doubt just set the loaded case on a flat hard surface and see if it rocks. If so the primer may be set high and be sticking out.

Primer that is too deep. possibly a pistol primer in a rifle case
Primer that is too deep. possibly a pistol primer in a rifle case

If you notice that the primers seem too deep then check and make sure you are using the right ones. A pistol primer in a rifle case may be too low and be noticeable deep. If that turns out to be the case, then remove and use the right primer. A handgun primer in a rifle case may under ignite the powder causing a weak round or hangfire. Removing a live primer isn’t dangerous if done carefully, wearing safety glasses is never a bad idea. While extremely uncommon, a primer can go off during loading and it may be a mechanical flaw with the equipment. That usually happens with the electric machines.

typical military crimp needs to be removed in order to properly prime
Typical military crimp needs to be removed in order to properly prime

If you load military cases, they have a crimp that has to be removed. A couple of companies make swages though personally I don’t care for them. I use a reamer attached to a drill. It may be time consuming but I don’t load large quantities of any ammo. Using a drill with a reamer works very well.

L.E. Wilson Case Chamfer Tool put on drill to ream out primer pocket crimp.
L.E. Wilson Case Chamfer Tool put on drill to ream out primer pocket crimp.

My reamer is a L.E. Wilson Case Chamfer Tool, that like everything else can be purchased at Brownells. Keep in mind that your ammo will reflect the amount of effort that was put into making it. If you cut corners and do a half way job the ammo will reflect that.

Priming system I use for handguns
Priming system I use for handguns

There are several ways to prime cases from the simple one at a time on a reloading press to various tools designed especially for that job. A progressive press also primes cases during the operation.

Brownells is my go to place if you are looking for a good selection for reloading equipment and supplies I would suggest that you pull up the Brownell website They have a large selection of priming and other reloading tools. The nice thing is if you are not sure what is best for your needs, just call one of their techs and they can steer you in the right direction on any reloading questions you may have. They also distribute reloading supplies such as bullets and cases.

Large on left and small primer pockets
Large on left and small primer pockets

Reloading Press Thoughts

At this time, I use a single stage press like the RCBS Rockchucker Supreme Press with the priming equipment that comes with the press. I do small amounts of custom and obsolete ammo, so for me that is practical. If you do a lot of ammo at one time then one of the many Progressive Presses will be more practical.

Tools I use for priming on a single stage press made by RCBS
Tools I use for priming on a single stage press made by RCBS

A typical progressive reloading press can do from 300 to 500 rounds an hour depending on a couple of factors. If you really produce a lot of ammo, there are larger, faster, and more expensive progressive units available. They all have the capability of priming during the reloading operation. I have used two progressives quite a bit and they do speed up the operation.

A Dillon 550 is a good progressive press
A Dillon 550 Reloading Press is a good progressive press model.

The Dillon 550 Reloading Press is a very popular press and is widely distributed. It has some advantages such as quick caliber change and a reasonable price. The same can be said for some of the other units in that price range. The Dillon has a guarantee and the only fault I find with it is the priming parts wear out so it is a good idea to have some extra parts available so when that happens the parts can be replaced easily. If the parts wear and are not replaced the priming will suffer. They may not feed or go in straight or some other annoying situation. Spare parts can ease that situation a lot. Dillon sells spare parts kits and I advise you to have at least one. I have used a Star Reloading Press a lot and the system is more complicated but never wears out.

There is an adjustment that allows you to seat the primers correctly but it is more costly then some of the other presses.

A couple of goofs a sideways and backwards primers both have to be removed
A couple of goof examples: a sideways and backwards primers, both have to be removed

If you are having problems priming your ammo brass, like properly seating the primers, there can be a couple of causes. Check everything to make sure nothing came loose as it may be that simple. Dirt or grease in the working parts will cause headaches though easy to remedy. Some progressive presses have adjustments that need to be reset from time to time. Star is one of those.

A Star progressive loading press. They never seem to wear out
A Star progressive loading press. They never seem to wear out

Sometimes if you change primer brands an adjustment may be necessary as some primer cups are harder than others. I have found that if a shell holder wears out in the groove the case isn’t tight and can cause a primer to go in crooked.

Large & small primers
Large & small primers

Again, a new shellholder can fix that problem easily. It is usually the simple things that makes a difference in how your reloads will turn out.

Priming ammo is easy and with the right tools it can also be a fun family effort. Reloading in general can be a great hobby as well as useful survival skill.

About Bob Shell:

A Custom Reloader of Obsolete and Antique Ammo, Bob Shell, writes about the subject of Guns, Ammo, Shooting and Related Subjects. For more information, visit:

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Clark Kent

Eye protection when handling primers is a MUST; not merely ‘never a bad idea’.

Ansel Hazen

I got to say Bob, that reamer for the primer pockets gives me the willey’s. I don’t see how you can possibly acheive any sort of consistency with that thing.

Try the Frankford Arsenal Primer Pocket Swager. It’s head and shoulders above the Dillon and RCBS products.


If you deprime and resize before cleaning and use a wet tumble with stainless pins, the primer pockets will be almost pristine. I do this and only have to give them a quick inspection before priming. If you’re loading rifle brass, might as well go ahead and trim at the same time as depriming/resizing.

Robert Cooper

So i did not see a fix on how to fix a side ways primer or one that does not go in all the way. I am a new reloader and was looking around for info on this thanks in advance great write up


Put it back through the depriming/resizing die. Just be very careful – it’s likely a live primer. Eye and hearing protection are a must. I’ve pressed live primers out of brass before. Haven’t had a single one go off on me [yet].

Fred H

Should trimming be done before of after sizing/decapping?


Process I follow:

1) Deprime/resize/trim/inspect
2) Tumble/clean/dry
3) Prime and flare
4) Add powder & load
5) Finish with a factory crimp

Ansel Hazen

My process is deprime with a universal die like the one from Mighty Armory.
Tumble 4 hrs in walnut media with a little White Diamond from the auto parts store.
Swage if needed for military brass
Trim inspect
Charge case with powder
Seat bullet
Light crimp on some rounds. .357 sig is one that crimping is essential.

Everything from tumble to swage is done in batches. After that on my Dillon 550c or smaller custom runs with my Lee Classic Turret.


Does Dillon 550c do “trim inspect” step. Don’t see how that fits between size and prime steps on progressive.

Jim in Conroe

For reloading with a single stage press, one variation on depriming / decapping is whether or not it should be done before or after case cleaning and sizing. If you do it before, the primer hole will get cleaned out by the cleaning media; if you do it after, you will need to use a tool, such as that mentioned in the article as an extra step in the reloading process.

I prefer to do it after cleaning, so that I work with a clean case in my sizing / decapping die.

Jon Brown

Cleaning the empty brass isn’t necessary. I haven’t cleaned a single case in 35 yrs. of loading. It just makes them pretty.

Jim in Conroe

I also decap and size after cleaning. I just don’t like to run dirty cases through my sizing die.

Roy D.

You mention the different heights of pistol and rifle primers. This only applies to large pistol and large rifle primers. Small pistol and small rifle are the same height.