FBI 12" Penetration Minimum Not Arbitrary - Confirmed in Recent Gel Test

[Low Budget Shooter]

Most of you already know that the FBI's 12" penetration minimum was established during the ballistics work done in the aftermath of the Miami shootout in which several agents were killed or wounded.

After the shootout, a comprehensive study of the wounds to the bad guys was done. One of the most-well-known findings was that in the opening salvo one of the agents scored an excellent hit on one of the bad guys with the 9mm 115 gr Winchester Silvertip. The bullet went through one arm and into the chest, stopping just short of penetrating the heart. That bad guy, after receiving that wound, went on killing and wounding FBI agents for several minutes. Everyone wishes for their sake that the agent's well-aimed shot had penetrated at least one more inch.

One of our favorite backyard ballistics gurus, tnoutdoors9, tested that round with his setup. It penetrated 11.25" in his gel test. Link: https://www.youtube.com/watch?v=HztD9GKtLUw

I suppose the FBI discovered the same in their extensive gel tests back in the late 80s, and that is where the 12" minimum came from, but I don't know that. But you can see for yourself that as to that particular scenario, the equivalent of 11" penetration in gel is what that round delivered in flesh, when the equivalent of 12" was needed.

What are your observations about that? Do you more experienced members know if that is how the FBI guys came up with the 12" minimum?

[Outpost75]

I was a civilian consultant to the FBI Firearms Unit at the time and worked with John Hall and Bill Vanderpool in developing the test methodology, relying heavily upon data provided by the Armed Forces Institute of Pathology and a panel of experienced field agent and forensic experts.

The 12-inch figure was arbitrary, but also based on satisfactory results obtained in the field with the .38 Special Winchester X38SPD, Remington R38S123 and Federal 38G 158-grain all-lead HP rounds. That level of performance deemed essential and the bureau also wanted that level of performance to be maintained as closely as possible in all of the various test conditions, bare gelatin being the baseline, then light clothing, heavy clothing, sheet metal, etc.

The 9mm ammunition available at that time was not sufficiently developed to meet that standard under all conditions. So until recently other interim rounds were used, while more field data was evaluated and the industry responded to user needs. Today's 9mm ammunition is MUCH more highly developed and is also street and military combat proven in counter-terrorist operations.

An ongoing program of ammunition development and product improvement has enabled the bureau to go back to 9mm without sacrificing performance. Sceptics can be confident that The Jello Man is not the last word in ammunition performance, but is a tool to get better ammunition into the field where its performance is proven beyond any doubt in operational use by law enforcement and military SOCOM units.

Since 9/11 they have had many opportunities to test in the real world and the rounds that work are no longer experimental, but available off-the-shelf and you can buy them.

[Low Budget Shooter]

Outpost, I'm very glad you chimed in with first-hand knowledge.

[mnewcomb59]

Google "handgun wounding factors and effectiveness" and find yourselves a copy of the pdf.

I'm a firm believer in ballistics testing. Many here are sneer at ballistics gel testing, but it is from their lack of understanding. The basics of the penetration testing is COMPARISON, not exactly predicting a bullets penetration in a bad guy or deer.
If bullet A penetrates 24 inches of gel and bullet B penetrates 16 inches of gel, you know that in a flesh and blood test that bullet B will not penetrate as far.

We also know that, after years of correlation with autopsies that bullets that penetrate 18" of gel tend to not exit people all the time. 18" gel penetration bullets tend to lodge between the ribs and skin of the back. Law enforcement and some private citizens are very worried about overpenetration.

"An issue that must be addressed is the fear of over penetration widely expressed on the part of law enforcement. The concern that a bullet would pass through the body of a subject and injure an innocent bystander is clearly exaggerated. Any review of law enforcement shootings will reveal that the great majority of shots fired by officers do not hit any subjects at all. It should be obvious that the relatively few shots that do hit a subject are not somehow more dangerous to bystanders than the shots that miss the subject entirely."

"Also, a bullet that completely penetrates a subject will give up a great deal of energy doing so. The skin on the exit side of the body is tough and flexible. Experiments have shown that it has the same resistance to bullet passage as approximately four inches of muscle tissue."

The FBI recommendation is that any bullets that penetrate less than 12" in bare gel, heavy clothing gel, through windshield glass or a certain gauge sheet metal are NEVER to be used for duty. Bullets that penetrate more than 18" can be used for duty, but over 18" penetration has a 50/50 chance or greater of exiting as the penetration increases.

"It is essential to bear in mind that the single most critical factor remains penetration. While penetration up to 18 inches is preferable, a handgun bullet MUST reliably penetrate 12 inches of soft body tissue at a minimum, regardless of whether it expands or not. If the bullet does not reliably penetrate to these depths, it is not an effective bullet for law enforcement use."

I am personally in the 18-22" penetration camp because I have seen first hand how exit wounds promote blood loss and lead to faster incapacitation. I prefer 9mm weighing 124 or more grains that expands, but expands to around 50 cal rather than 62. Same thing with 45. I prefer bullets that expand around 55-60 cal and 18"+ penetration rather than 70 cal with 12" penetration. In a perfect world, my ideal handgun bullets for deer and defense would fully penetrate and exit reliably at 200 fps or less. I have also run plenty of hard WFN bullets, but if you can gain a little bullet diameter and still exit you are maximizing your damage potential. I am much more of a fan of softer WFN bullets that turn into sharp full wadcutters.

[Outpost75]

I am also a big fan of the Full Charge Wadcutter:

https://www.luckygunner.com/lounge/w...-self-defense/

In the 1970s both Remington at Bridgeport, and Winchester at New Haven, CT loaded "full charge" wadcutters which were originally intended as training and practice ammunition by the NYPD. The rationale, according to Frank McGee who headed the firearms unit back in the day, was that they didn't want cops practicing with "light target loads" but wanted the wadcutter bullet assembled into the case using the same powder charge then common for 158-grain LRN service ammo, so that the recoil would be similar. Velocity was about 800 fps from a 4" S&W Model 10 or Colt Police Positive, blue square-butt .38 Special "cop gun" which was then issued.

The story told to me by Bill Allard, was that Jim Cirillo and others in the Stakeout Unit realized a good thing when they saw it and took this new practice ammo to the street, where it performed much better than the "official" LRN service ammo. When questioned by the shooting review board, to a man they stuck with their story, "we came from the range and the wadcutter ammo was what we had with us" and the rest is history.

Check Grant Cunningham's blog for loading recipes courtesy of former NRA Tech Staffer Ed Harris, who got the story from the horse's mouth.

http://www.grantcunningham.com/2011/...rge-wadcutter/

Related:

http://www.shootingtimes.com/ammo/am...btests_200807/

Based on AFIP’s photo-interpretation system, the energy transfer numbers were around 110 ft-lbs for the 9mm Luger FMJ and 120 ft-lbs for the .45 ACP FMJ... According to the AFIP criteria, ammo transferring 150 ft-lbs produced a temporary cavity twice that of the .38 LRN producing 75 ft-lbs... At standard velocity, the SWC posted a small but statistically insignificant advantage over the LRN loads. At what today would be .38 Special +P velocities–the +P indicator was not standardized until 1974–the SWC showed a modest advantage, posting transfers of around 95 to 135 ft-lbs depending on make and velocity. For giggles, we shot some 148-grain hollow-base wadcutter ammo; it consistently hovered at 145 ft-lbs transfer!