Anyone involved in modern gun culture knows that the FBI Standard gel tests have become, uh standard, in the gun community, but I see posts all the time by people that clearly don’t understand what these tests represent.

What is it?

In the 1980s the FBI had several instances where their standard service rounds underperformed in actual shootings. By this I mean that they failed to penetrate deeply enough to interrupt vital structures to incapacitate the suspect. The FBI took a two-pronged approach to addressing this. One was to issue bigger, more powerful pistol rounds like the 10mm and later the .40 S&W when that proved to be difficult for the average agent to manage. The second was to try to develop a standard test to determine if a specific cartridge and bullet would do the job.

The criteria they arrived at was this: A bullet had to reach the stuff you need to break to make the bad guy stop doing the thing that made it necessary to shoot them. This meant that penetration was Job #1. Next you had to actually hit the things you needed to break, so accuracy came in second. Lastly since pistol bullets tend to only damage tissue they physically touch it would be desirable for the bullet to expand. Bigger bullets touch more stuff. Not a lot more stuff, mind you, but every little bit helps.

The FBI wanted to establish a standard for bullet performance that was grounded in reality, and gel tests at the time were a terrible predicter of real-world performance because humans have, you know, bones and stuff. They are also disinclined to stand still facing you in a full-frontal position. In the chaos of a gunfight a bullet might need to pass through obstacles, cross through the body at odd angles or hit things like an arm before they encounter the important stuff. Also variable amounts and thicknesses of clothing could affect the performance of hollow-point ammunition.

This being the case they took a pretty rational approach. They took bullets that worked well in their real-world shootings and checked to see if they performed similarly in a standardized test. As it turns out they did. Thus the ‘FBI Standard’ was established.

The Basic standard that is broadly referenced today is that a bullet fired through four layers of 16-oz. denim must pernitrate calibrated ballistic gel to a depth between 12 and 19 inches and it was highly desirable for the bullet to expand and create a larger permanent wound track. Pistol bullets generally do not have the energy to create hydraulic tearing of tissue; they typically only create damage to tissue they physically touch. The temporary would cavity might in some cases create a shockwave intense enough for it’s impact on major nerves to produce a stunning effect (called Neural Shock) but in reality human internal structures are such an inconsistent media that they felt this was such an unreliable mechanism that it could effectively be disregarded.

What Does it Mean?

FBI spec tests are comparative rather than predictive and represent a performance standard only. ‘Bullets that work well in real life all perform to this standard in this media, so it is reasonable to presume that bullets that meet this standard will also perform well in real life shootings.’ That makes a certain amount of sense and it seems to have been largely borne out in practice.

Real wound tracks very much don’t look like wound tracts in gel at all; the variable elasticity and toughness of different types of tissue a bullet encounters in situ produces a very different result in gel. Then you introduce bone and things get really complicated.

This doesn’t mean that bullets that *don’t* meet FBI Standard aren’t useful. Individual self-defense shootings are seldom ‘gunfights’ as such even when both parties are holding firearms. A bullet that does not meet FBI standards has an enhanced chance of failure in some of the circumstances that occur in the sort of gunfights the FBI has found itself in but that doesn’t mean they are necessarily useless.

This is why I find Paul Harrell’s Meat Target a useful adjunct to gel testing as it does create a somewhat more realistic analogue to a human torso, so looking at that alongside results in gel creates a useful expansion to the data set.

There are Exceptions to Every Rule

There are bullets that have performed well in real life that do not follow ‘The Rules.’ Apparently there really is more than one way to skin a cat. The first of these are the Lehigh Extreme Defender rounds. These meet the basic FBI standard and in real-world tests on flesh produce similar wounds to modern high-quality hollow-point ammunition despite the fact that they do not expand.

The bigger, more controversial exception are Glaser Safety Slugs. These are a high-velocity pre-fragmented projectile that break up on penetration. These underpenetrate badly in FBI standard tests but in documented (this is an important word) real-life shootings they have performed similarly to modern JHPs.

Yes, internet mythology is rife with reports of failures-to-stop and I know of two documented instances where a single hit failed to stop an attacker. After researching these it turns out that these were marginal hits that would likely have failed even with a conventional bullet. The most famous myth is about one breaking up on a metal button on a leather jacket. I was actually able to track down an instance where this occurred and spoke to the Medical Examiner in the case ‘off the record.’ A 9mm Glaser did indeed strike directly on a metal button on a leather coat. The result was that the mangled button was found adjacent to the suspects spine after having passed entirely through his chest cavity and he ‘dropped like a pole-axed steer.’

Though Glaser slugs appear to be effective the data set is quite limited and I do not recommend them for general carry. The bullets are very velocity-dependent and because they are light-for-caliber they shed energy quickly in flight. For uses where ranges are short and overpenetration is a serious threat to innocents I think they are alright. When I lived in a small apartment with paper-thin walls and children living next door I loaded my home-defense pistol with them. I have also, sadly, found them ideal for mercy shots to the skull dying critters.

So There it is.

Conformance to the FBI Standard makes it more likely that a given bullet will do it’s job under a broad spectrum of conditions. Failing to meet that standard does not mean that a bullet is inherently ineffective or will not serve for everyday self-defense uses. BUT since there is no such thing as a ‘typical’ use of deadly force in self-defense I consider it prudent to use ammunition that conforms to the FBI standard.

Stay safe and take care,

Michael Tinker Pearce, 31 October 2023

Happy Halloween!