Anatomy of a Misfire

By Guy Neill

Modern ammunition is amazingly reliable. Problems, given the number of rounds manufactured, are extremely rare. They are rare enough that the shooter may be at something of a loss as to what to do if they experience a misfire. Understanding the potential causes of misfires and how to handle them could save your gun and possibly your life.

If you do experience a misfire, where the gun goes “click” instead of “bang,” the first thing to do is wait a few moments with the gun pointed in a safe direction to ensure it isn’t a hangfire (a delayed discharge). Once you are sure it’s safe to extract the cartridge, continue to keep the gun pointed in a safe direction and examine it. Take the round out of the chamber and see if the round has a firing pin indentation on the primer. Is the bullet still in the casing?

If the bullet was left somewhere in the bore, that indicates the primer fired and pushed the bullet out of the case, but failed to ignite the powder charge (if there was a powder charge).

Is there any unburned powder in the mechanism of the gun? If there is no powder evident, it likely indicates there wasn’t powder in the cartridge, and was not a true “misfire.” This is still a problem, however. If the bullet was driven into the bore, it’s a more serious problem than a true misfire and you’ll have to remove it.

If there is powder in the action of the gun, that means the primer failed to ignite the powder charge. There can be several reasons for this.

If you didn’t note whether or not there was powder in the action, examine the bullet once it’s removed from the bore. If the base of the bullet is clean, it indicates there was powder in the cartridge. A bullet with a blackened base tells us it was a primer-only event. It wasn’t a true misfire, but an indicator of a cartridge failure.

Contamination of the powder is one reason the powder may have failed to ignite. If water, oil, or some other contaminate gets into the powder charge, that can prevent the powder from burning. Characteristics of contamination include clumping of the powder or oiliness.

Another possible cause of a charge failing to ignite is the priming compound being contaminated. This is more difficult to check and is best left to the factory rather than trying to check it yourself.

It’s not common, but there have been occurrences of the primer not having enough priming compound. This may result in the primer firing, but with too little priming compound, it may not generate enough of a spark to ignite the powder. There’s no way to tell from examining that primer, though, unless it did not fire at all. Again, this sort of determination is better done by the manufacturer.

Even more rare, but not unknown, are primers that somehow left the factory with no priming compound at all. The factory can likely determine if this was the cause by examining if there is any residue of the priming compound in the cup.

If there is no indentation in the primer from the firing pin, then it’s not a true misfire. Instead, it indicates a problem with the firing mechanism of the gun. Something prevented the firing pin from making contact with the primer.

Or, the cause may be a bit more mysterious. Some years back we had a revolver shooter in our group shooting practical pistol competitions. In rapid fire his revolver would sometimes misfire. Or so we thought.

He had the gun checked, and the gun smith could find no problems. Still, the problem persisted and even progressed. It gave an increasing number of misfires in a single cylinder.

Looking at the cartridges after he had problems, we saw there were clear firing pin indents in the rims of the cartridges that had not fired. The cylinder was not locking up appropriately and turned past the locking notch, allowing the firing pin to strike the rim instead of the primer.

We dropped some light oil on the pivot points inside the revolver and reinstalled the sideplate. The gun performed reliably – firing all chambers as it should. Apparently there was old oil or debris that was interfering with the mechanism – as in preventing the locking bolt from engaging as it should. The oil washed it away and provided enough lubrication to allow proper function.

If there is an indent, the misfire could still be the fault of the gun. If the firing pin broke, or if the spring driving the firing pin or hammer is weak or broken, it may not be able to deliver sufficient energy to the primer to ignite it. This sort of indent will appear shallower than a normal firing pin blow.

If the gun checks out, the primer becomes the focus of the misfire. The leading cause of misfires with reloaded ammunition is primers that are not fully seated. Fully seated is defined as the primer anvil legs being seated against the bottom of the primer pocket. If the primer is not completely seated, the firing pin strike can move the primer deeper into the primer pocket, robbing energy from indenting the primer cup as it should.

Characteristically, misfires of this type have firing pin indentions that look light. Should you choose to try to fire the cartridge a second time and it fires, it’s certain that this was the problem. A second (and, rarely, a third) firing pin strike firing the cartridge indicates the first firing pin strike completed seating the primer and it functioned as it should on the second strike.

But it may not fire even if this was the problem. The first firing pin strike may have broken the priming compound inside the primer, leaving little or no priming compound to be crushed between the anvil and the primer cup indention. In this circumstance, the cartridge has little probability of firing no matter how many times it is struck by a firing pin.

Such primer seating problems are virtually never seen in factory ammunition because of the quality checks used. Still, there have been some.

To recap, a true misfire is when the primer fails to ignite when struck by the firing pin. There can be several reasons. What appears as a misfire may be a cartridge failure where the primer actually fires, but the cartridge does not propel the bullet out of the bore.

If the misfired or failed cartridge is a factory cartridge, the manufacturer wants to know about it. Having the production lot number will help them.

Fortunately, problems with ammunition are rare. Problems can arise, and knowing how to assess any that do occur can allow the shooter to eliminate potential future problems.