Ammunition problems. Bullet casings with various imperfections.

As with any product, ammunition can exhibit problems regardless of the quality of the product chosen. With ammunition issues, however, these malfunctions can range in severity from minor annoyances to life-threatening catastrophes.

In this article, our Ballistician, Paul Bradley, offers some top tips on diagnosing problems with ammunition and identifying which malfunctions are caused by the weapon system, or in some cases, a combination of both. Paul breaks down these individual issues in detail and provides simple steps that users can take to avoid them. 

Weapon System Vs Ammunition

When it comes to malfunctions in weaponry, people are quick to blame their ammunition for several reasons. Of course, ammunition can be faulty. But there are, however, many weapons and system related issues that can cause what appears to be an ammunition failure but is actually something else entirely.

I’ve been making and testing ammunition for many years and have spent the last 6 years as an Armourer and Ballistician in the defence sector. When I am called upon to assess an “ammunition issue”, nine times out of ten it ends up being a weapon issue.

Ammunition, when purchased from a reliable manufacturer has been given a significant quality inspection. At Primetake, we operate in an ISO9001 quality standard environment, as do most of our component suppliers. Each ammunition component has been inspected by the manufacturer, by us at goods in, then again during the build and once more following the proof of a lot. We proof to British standards unless otherwise stated.

The chances of rogue components or ammunition slipping through the net are small. Weapons, on the other hand, are often old, abused, or incorrectly serviced/maintained, the list goes on. Gun malfunctions are far more common than people think. Below are some common issues I have seen in weapons that are mistakenly diagnosed by users as ammunition faults.

Weapon Fouling

Most of the weapon problems I encounter are down to a dirty chamber/bore/gas system or moving parts. This can have a variety of effects, including inaccuracy, failure to cycle, failure to fire, or overpressure, and articles can become lodged in the bore. Of course, the latter two of these issues can have serious consequences.

So, how often should a firearm be cleaned? I’ve seen weapons with several millimetres of carbon build up, which has led to significant overpressure. This was down to a failure to adhere to the manufacturer’s recommended cleaning and maintenance regimen. In short, there’s no set answer. Weapons should be cleaned according to manufacturer recommendations and within their suggested timeframes.

A pierced primer which has been partially forced out of the primer pocket by high pressure due to excessive fouling.
A pierced primer which has been partially forced out of the primer pocket by high pressure. In this case, the weapon was found to have excessive fouling in the chamber and bore.

Gun Barrel Erosion

A worn barrel can also cause a multitude of problems. There are no set limits on barrel life but, if left for too long, the user will start to notice inaccuracies and possibly a loss of velocity or enlarged velocity spread. A competent armourer will know the approximate round count for various calibres and can bore scope them when needed to assess their condition.

Erosion can also cause headspace issues. Headspace is the dimension between the bolt face and a limiting chamber feature which prevents a cartridge from moving too far forward in the chamber. Headspace can change over time due to erosion and this can cause several issues.

You may notice increased light strikes/misfires, where the cartridge has been able to slip forward far enough that the firing pin is unable to strike the primer with enough energy to set it off. If the primer does go off and the headspace is too large, then the case is likely to tear open or separate completely. This can lead to a catastrophic failure in the weapon and significant danger to the user.

Headspace can also be too small. This is generally caused by poor engineering, manufacturing, or gunsmithing. When headspace is too small, the bolt will not generally close. If it does close, there could also be an overpressure issue. Headspace can be assessed by a competent armourer using Go/No Go Gauges.

The casing of this ammunition has separated due to a headspace issue (too much headspace).

This case has separated due to a headspace issue (too much headspace).


Semi Auto systems and Non-adjustable Gas

A round fails to chamber in a semi-automatic firearm.
A round fails to chamber in a semi-automatic firearm.

If you are using a semi auto system along with off the shelf ammunition, then you could end up disappointed. Most semi auto carbines and rifles destined for the civil market feature a fully adjustable gas block.

There is a good reason for this – the firearms manufacturers realise that this offers the best chance of their products functioning with a variety of ammunition brands and natures. Firearms made for Mil/LE tend to have a fixed gas system (or, at most, 2 stage) to prevent users from fiddling with it. This would be great if it then offered completely reliable performance. The reality is that you will likely end up with a very ammo fussy firearm. This is where agile manufacturers like Primetake can help, by providing products that operate reliably within the confines of a fixed gas system.

The types of failure you’re likely to encounter due to gas system/ammunition incompatibility are failure to feed (pictured above) and failure to fire or fully eject, which can lead to a case becoming lodged in the chamber or above the magazine.

Over-gassing can blow primers out of the back of the cartridge blocking the trigger mechanism. This is more common in large frame designs. A lack of sufficient gas can cause the bolt carrier group to fail to reach its full rearward position. The next round will then fail to be picked up and the bolt will glide over the top of it, resulting in a “dead man’s click”.

 The bolt on this AR platform can be seen gliding over the top of the rounds.
The bolt on this AR platform can be seen gliding over the top of the rounds.

Firearm Cleaning Products

The cleaning products used on the firearm can also have an impact on its performance, especially for semi autos. Some cleaning products can become tacky in cold conditions, and many products will react if used in combination with another firearm cleaning product of a different brand.

Overuse of cleaning products can also be an issue. Too much oil in the chamber or bore can lead to overpressure or case deformation. Excess product will also attract dust and carbon, which can form a gum-like residue and can lead to slow-moving parts.

The case has been pushed in due to excess oil in the chamber.
The case has been pushed in due to excess oil in the chamber. This failure can also occur due to work hardened necks failing to obturate and allowing gas to flow backward between the case and chamber wall.

Unsuitable Barrel Twist/Projectile Weight

In general terms, a heavier, longer projectile, requires a higher rate of spin to remain stable throughout its trajectory.

Failure to correctly pair your barrel’s twist with an ideal projectile weight will lead to instability and the projectile will be less accurate. I have also witnessed very tight twist rates (1-5” for example) tear expanding projectiles apart as they leave the muzzle. This could damage suppressors or muzzle brakes and could pose a risk to anyone standing to the side of the muzzle.

Faulty Firearm Systems

There are some firearms on the market which have quality issues from the start or have been subject to multiple changes or recalls for internal parts. If, for example, a semi auto firearm with a fixed gas system has multiple variations on the market (various upgraded internal parts), then it becomes almost impossible for ammunition manufacturers to offer products which reliably cycle with all variants. This is exacerbated when the end user requires the system to operate in temperature ranges such as +52c/-54c (common Mil/LE requirement).

Unsuitable Firearm Upgrades

The addition of items such as custom muzzle brakes/suppressors and even magazines can all influence the system’s ability to function. Subsonic ammunition in a semi auto system is particularly sensitive to suppressor selection. Another reason why firearms/ammunition/accessories are now commonly sold as a “system”.

Feed and ejection issues can be caused by poorly selected muzzle devices or suppressors.
Feed and ejection issues can be caused by poorly selected muzzle devices or suppressors.

Ammunition problems

There are, of course, instances where ammunition is to blame. In my experience, this tends to be far less common than firearm related issues and is more often seen with ammunition that is very old or has been incorrectly stored.

People often ask me ‘do bullets go bad?’ or ‘how long does ammunition last?’

Propellant and primers degrade over time, but the timescales are generally quite long. 10 years is the typical duration for how long bullets last. However, these timeframes can drop dramatically when the manufacturer’s storage instructions are not adhered to.

Heating and cooling, especially at extreme temperatures, will cause the chemicals in the propellant and primers to degrade at a much greater rate. A good ammunition manufacturer will make you aware of their ammunition’s shelf life and storage parameters.

Propellant Charge Weight Issues

By far the most common issue I come across in terms of subpar ammunition performance relates to variations in charge weight.

If your ammunition is at the cheaper end of the scale and is rolled off an automated production line, then the variation can be large. A large variation results in increased velocity spread and thus inaccuracy and vertical stringing.

At longer ranges, this is particularly noticeable, and rounds are likely to make impact above and below the target. The larger the variation the lower the average charge weight must be to ensure ammunition does not exceed safe pressure


Ammunition which has been overcharged with propellant can result in overpressure. If you suspect overpressure (because the weapon cycles erratically or the bolt becomes hard to lift/operate), then you should inspect your ejected brass.

If you see primers that are cratered, flattened, pierced, or partially/completely blown, or cases with significant marks or swipes on the headstamp, then it would be wise to assume you are running at too high of a pressure for that system and are possibly exceeding CIP or SAAMI specs.

This case shows signs of overpressure. The round has a pierced primer, a flattened primer, and a swipe mark on the headstamp.
An example of a cartridge case which demonstrates clear signs of overpressure. This was a “home reloaded” round which has a pierced primer, a severely flattened primer, and an obvious “swipe mark” across the headstamp.

Dimensional Issues

The simplest of issues relate to overall length. A round that is to long will not chamber or may push the bullet hard against the lands (rifling), leading to overpressure. Although there are specifications which dictate overall length (CIP for example), this does not always suit all firearms.

Some bullets have a pronounced Ogive (curve at the front of the bullet), which requires a shorter seating depth in some specific systems. This is quite common and is another reason why it is vital that you select an ammunition supplier who understands this.

It is also possible that commonly accepted calibre crossovers may cause issues. While 308Win/7.62x51mm may be interchangeable in some systems, they are not always and can lead to overpressure. Again, a good manufacturer will be able to advise on this.

Incorrect Crimping or Sealing

It is common practice for ammunition manufacturers to pull test bullets. This ensures bullets cannot be pulled out of the case when extracted from the chamber without having been fired (a common practice for patrols who rarely need to use weapons operationally).

This also prevents bullet setback, wherein the bullet is pushed further into the case (as can be seen in the picture below).

Firing a cartridge with bullet setback could cause a significant overpressure and would, at the very least, be highly inaccurate. Failure to seal the rounds properly will allow moisture ingress over time, especially in highly humid environments.

Rounds that are subjected to moisture internally are likely to misfire or become a squib load. A squib load (also known as a ‘pop and no kick’, a squib round, or just a squib, is a firearm malfunction where a projectile lacks the necessary force to leave the barrel and therefore gets stuck. Both gun misfires and squibs can be highly dangerous for end users. A squib load may retain enough energy to push a bullet part way down a barrel, but the next round fired would then create a huge overpressure and would likely lead to a catastrophic weapon failure.

A squib round


This article by no means details every scenario that may go wrong with a weapon or with ammunition. It represents those that you are most likely to encounter as a regular user.

It is vital that users select premium quality ammunition and preferably ammunition which is proven to work well with the system they are using.

Buying blindly off the shelf can be a false economy, no matter how tempting the price may seem. It is entirely possible you could procure firearms and ammunition, both of which meet their correct specification (CIP, SAAMI, NATO, etc.), but they may simply not work well or even at all when used together. Therefore, the purchase of a “system” which encompasses both firearms, optics, accessories, and ammunition is becoming increasingly commonplace within the defence industry.

As a premium producer, Primetake can manufacture ammunition which is specifically designed for the user’s chosen system; ensuring reliable, safe function across a wide temperature and environmental range.

The Primetake team and I are always happy to provide advice and solutions on all things ammunition. Feel free to get in touch and we’ll help where we can.

Mass produced ammunition sold cheaply. This cartridge has no flash hole.
Here we can see mass-produced ammunition sold at a lower price point with an unusual flaw – there is no flash hole. When the primer was struck, the gas pressure had nowhere to go and thus pushed the primer out of the pocket. The primer fell into the trigger mechanism, preventing the firearm from being used even if another working round was chambered. Headstamp hidden.