Anyone familiar with the 1986 FBI Miami shootout and the follow-up research into the failures to stop the bad guys knows that the FBI recommends a minimum of 12 inches and maximum of 18 inches of penetration in a duty load. The idea is that while a bullet hitting the target straight on might only need a few inches to reach the vitals, if the bullet has to travel at an oblique angle and/or if it has to pass through an arm first, you are going to need something that can go the recommended 12-18”.
Many self defense enthusiasts (like me) have latched onto this number as the golden rule. If it’s good enough for FBI duty loads, it’s good enough for self defense loads, right? Well, in theory yes. The FBI shooting a perp has the same goal as a civilian shooting an assailant – to stop the bad guy. However, I was watching a Youtube video where the guy was testing various types of ammo to find those which worked “best” in his handgun, and he automatically rejected anything that went over 18” in gel, because it “overpenetrated.” This got me thinking…
The way I see it, you have two extreme situations described above. Scenario A is when the bad guy is squared off against you. His arms aren’t in the way, his chest is at a 90 degree angle across your bore, and the bullet only needs a couple inches to hit the vitals. Scenario B is the worst case scenario the FBI looked at, where you need 12 inches or more. A bullet that goes 15” in gel is just perfect for scenario B, but will greatly overpenetrate in scenario A.
This is the justification some people have for going with underpenetrating ammo, and I can see their point. My point is, if I have a round that will go 20”, it might “overpenetrate” in scenario B, but any round deemed worthy will overpenetrate in scenario A, and any round will vastly overpenetrate on a miss (which it is a common assumption you will have 30% accuracy in a shootout).
You can draw your conclusions from that if you wish. I personally say more than 12” is good, under 18” is fine, but not necessary. However, this train of thought, and watching some more ballistics gel videos, led me to another train of thought on the same subject. I realize bringing up underpenetration vs. overpenetration is a forum taboo, so I’ll make up for that by bringing up 2 more:
Rifle vs. Shotgun vs. Pistol
Buck-and-Ball (and other similar gimmicks)
Let’s look at some common wound tract paths (that I quickly drew in Paint just to give you an idea of what I’m thinking about):
Pistol
The pistol wound tract is likely from a JHP round designed to meet FBI specs in at least one barrel length. Chances are it is something like a 9mm bullet expanded to 0.5” or a .45 expanded to 0.65”, or something in between. Maybe it expanded more and penetrated less, or maybe it failed to expand and poked all the way through.
The important thing is that from just after the start until it stops, the JHP round is a consistent width. You get that 0.5” hole from start to finish. In scenario A or scenario B you will have a 0.5” hole through the vitals (if you hit the vitals). The hole isn’t going to be very big anywhere, but pistols are a compromise.
The other big benefit to pistol rounds (if fired from a long gun) is follow-up shots. Pistol rounds do the job for very little recoil on the shooter, meaning follow-up shots are quick and easy.
Rifle
The wound tract from a common home defense rifle with high-velocity ammo is going to look like a snake that has just eaten something much fatter than itself. You will have a small neck (bigger if the ammo takes a while to fragment or yaw) of bullet diameter, and then a HUGE wound cavity from where the round dumped its energy in yaw and/or fragmentation. That giant wound cavity will generally fall short of the 12-18” penetration mark (usually about 8-10” mark), and what you’re left with is the remainder of the bullet passing through the rest of the gel.
In scenario A, this means the rifle is absolutely devastating. If the vitals are 3-6” deep, then a wound tract that extends from 2-8” is perfect for disrupting the target’s ability to fight. You’ll have a small core with much less velocity on the way out of the massive exit hole, which will put the target down in very short order.
In scenario B, you end up with a lot of damage through the initial tissue, but your actual wound tract through the vitals is only the size of the remaining core. This may be an expanded chunk with jagged edges, or it may just be a tiny rod the size of a .22 LR bullet. Now, that tissue damage and all those open blood vessels will help slow the target down, but the actual damage to the vitals is likely going to be comparable to what you could expect from a .22 LR.
With that said, follow-up shots are an important factor as well. Chances are not every shot will need quite the penetration as the worst-case-scenario shot. People like rifles in .223 over shotguns because you can follow-up quicker, and you have a lot more in reserve in the magazine. Thus, even if you don’t get the vitals in the “sweet spot” for the rounds you’re using, you have a lot of firepower to create a cumulative effect on the target.
Shotgun
Some liken the shotgun to a submachine gun, because you get several wound tracts per trigger pull. It’s not a perfect analogy – an SMG would more likely be loaded with hollow-points, meaning a much wider wound tract. Still, the shotgun is likely to produce several deep-penetrating wound tracts of 1/3 inch or a couple dozen at ¼ inch. While each wound tract is relatively small, what you get are multiple attempts to hit the vitals per pull of the trigger.
Where the rifle’s sweet spot is near the beginning of its wound tract, I feel the shotgun gets better the further it goes in. The pellets slowly spread out, giving you more coverage to hit something important. So in scenario A you get a ragged hole through where you hit, but in scenario B you are incredibly likely to hit something important. However, I think this is much better in scenario A than the rifle is in scenario B, at the cost of greater recoil.
Special
I’m not talking about .38s and .44s here; I’m talking about the special rounds you see people offering mixed shotgun loads like buck-and-ball, or the new G2 RIP ammo. The G2 RIP, for example, has petals that penetrate about 4-5” and look like a scaled-down shotgun blast, and then a penetrating 9mm core that goes through to about 16”.
I used to look at buck-and-ball loads and say “if you need a slug, just get a slug and forego the extra recoil of the underpenetrating buckshot. If buckshot will suffice, then get rid of the slug, add several pellets of buckshot, and increase the surface area of your wound tract.” However, the different scenarios above got me thinking:
In scenario A, the penetrating core of the G2 RIP will overpenetrate, but so will any defense load. However, you get a nice wound tract through the vitals that you wouldn’t get with just a solid projectile.
In scenario B, the lesser-penetrating fragments cause superficial damage, just like a fragmenting hollowpoint (Glaser safety slug, anyone?). However, the penetrating slug continues through like an FMJ, except it doesn’t go too far.
What do these multi-depth wound tracts look like? Well, it’s not exactly the same as a rifle round, but it seems to be pretty close. You get a large wound tract in Scenario A and a smaller, stable tract through Scenario B. Like I said, I know it’s not exactly like a rifle. It’s a lot of little wound tracts that look like one big one when viewed from the side, whereas the rifle tract is big even in cross-section.
Conclusions
This is a big long post that basically is just me looking at different wound tracts and how they apply to the 12-18” rule, or how they apply in a best-case scenario. I still don’t think I would go with a multi-depth round like buck-and-ball or G2 RIP, but I can see the case being made for them.
I have to say that overall, it makes me question the effectiveness of a rifle over a shotgun or pistol round. It’s easy to say that they penetrate well and they have a giant PWC, but it’s also plain from most of the gel tests I’ve seen that in the “magic” 12-18” mark, most of the energy from the rifle round has been dumped and you’re left with the small remainder. Like I said, though, 30 in the box certainly helps make up for it.
Many self defense enthusiasts (like me) have latched onto this number as the golden rule. If it’s good enough for FBI duty loads, it’s good enough for self defense loads, right? Well, in theory yes. The FBI shooting a perp has the same goal as a civilian shooting an assailant – to stop the bad guy. However, I was watching a Youtube video where the guy was testing various types of ammo to find those which worked “best” in his handgun, and he automatically rejected anything that went over 18” in gel, because it “overpenetrated.” This got me thinking…
The way I see it, you have two extreme situations described above. Scenario A is when the bad guy is squared off against you. His arms aren’t in the way, his chest is at a 90 degree angle across your bore, and the bullet only needs a couple inches to hit the vitals. Scenario B is the worst case scenario the FBI looked at, where you need 12 inches or more. A bullet that goes 15” in gel is just perfect for scenario B, but will greatly overpenetrate in scenario A.
This is the justification some people have for going with underpenetrating ammo, and I can see their point. My point is, if I have a round that will go 20”, it might “overpenetrate” in scenario B, but any round deemed worthy will overpenetrate in scenario A, and any round will vastly overpenetrate on a miss (which it is a common assumption you will have 30% accuracy in a shootout).
You can draw your conclusions from that if you wish. I personally say more than 12” is good, under 18” is fine, but not necessary. However, this train of thought, and watching some more ballistics gel videos, led me to another train of thought on the same subject. I realize bringing up underpenetration vs. overpenetration is a forum taboo, so I’ll make up for that by bringing up 2 more:
Rifle vs. Shotgun vs. Pistol
Buck-and-Ball (and other similar gimmicks)
Let’s look at some common wound tract paths (that I quickly drew in Paint just to give you an idea of what I’m thinking about):
Pistol
The pistol wound tract is likely from a JHP round designed to meet FBI specs in at least one barrel length. Chances are it is something like a 9mm bullet expanded to 0.5” or a .45 expanded to 0.65”, or something in between. Maybe it expanded more and penetrated less, or maybe it failed to expand and poked all the way through.
The important thing is that from just after the start until it stops, the JHP round is a consistent width. You get that 0.5” hole from start to finish. In scenario A or scenario B you will have a 0.5” hole through the vitals (if you hit the vitals). The hole isn’t going to be very big anywhere, but pistols are a compromise.
The other big benefit to pistol rounds (if fired from a long gun) is follow-up shots. Pistol rounds do the job for very little recoil on the shooter, meaning follow-up shots are quick and easy.
Rifle
The wound tract from a common home defense rifle with high-velocity ammo is going to look like a snake that has just eaten something much fatter than itself. You will have a small neck (bigger if the ammo takes a while to fragment or yaw) of bullet diameter, and then a HUGE wound cavity from where the round dumped its energy in yaw and/or fragmentation. That giant wound cavity will generally fall short of the 12-18” penetration mark (usually about 8-10” mark), and what you’re left with is the remainder of the bullet passing through the rest of the gel.
In scenario A, this means the rifle is absolutely devastating. If the vitals are 3-6” deep, then a wound tract that extends from 2-8” is perfect for disrupting the target’s ability to fight. You’ll have a small core with much less velocity on the way out of the massive exit hole, which will put the target down in very short order.
In scenario B, you end up with a lot of damage through the initial tissue, but your actual wound tract through the vitals is only the size of the remaining core. This may be an expanded chunk with jagged edges, or it may just be a tiny rod the size of a .22 LR bullet. Now, that tissue damage and all those open blood vessels will help slow the target down, but the actual damage to the vitals is likely going to be comparable to what you could expect from a .22 LR.
With that said, follow-up shots are an important factor as well. Chances are not every shot will need quite the penetration as the worst-case-scenario shot. People like rifles in .223 over shotguns because you can follow-up quicker, and you have a lot more in reserve in the magazine. Thus, even if you don’t get the vitals in the “sweet spot” for the rounds you’re using, you have a lot of firepower to create a cumulative effect on the target.
Shotgun
Some liken the shotgun to a submachine gun, because you get several wound tracts per trigger pull. It’s not a perfect analogy – an SMG would more likely be loaded with hollow-points, meaning a much wider wound tract. Still, the shotgun is likely to produce several deep-penetrating wound tracts of 1/3 inch or a couple dozen at ¼ inch. While each wound tract is relatively small, what you get are multiple attempts to hit the vitals per pull of the trigger.
Where the rifle’s sweet spot is near the beginning of its wound tract, I feel the shotgun gets better the further it goes in. The pellets slowly spread out, giving you more coverage to hit something important. So in scenario A you get a ragged hole through where you hit, but in scenario B you are incredibly likely to hit something important. However, I think this is much better in scenario A than the rifle is in scenario B, at the cost of greater recoil.
Special
I’m not talking about .38s and .44s here; I’m talking about the special rounds you see people offering mixed shotgun loads like buck-and-ball, or the new G2 RIP ammo. The G2 RIP, for example, has petals that penetrate about 4-5” and look like a scaled-down shotgun blast, and then a penetrating 9mm core that goes through to about 16”.
I used to look at buck-and-ball loads and say “if you need a slug, just get a slug and forego the extra recoil of the underpenetrating buckshot. If buckshot will suffice, then get rid of the slug, add several pellets of buckshot, and increase the surface area of your wound tract.” However, the different scenarios above got me thinking:
In scenario A, the penetrating core of the G2 RIP will overpenetrate, but so will any defense load. However, you get a nice wound tract through the vitals that you wouldn’t get with just a solid projectile.
In scenario B, the lesser-penetrating fragments cause superficial damage, just like a fragmenting hollowpoint (Glaser safety slug, anyone?). However, the penetrating slug continues through like an FMJ, except it doesn’t go too far.
What do these multi-depth wound tracts look like? Well, it’s not exactly the same as a rifle round, but it seems to be pretty close. You get a large wound tract in Scenario A and a smaller, stable tract through Scenario B. Like I said, I know it’s not exactly like a rifle. It’s a lot of little wound tracts that look like one big one when viewed from the side, whereas the rifle tract is big even in cross-section.
Conclusions
This is a big long post that basically is just me looking at different wound tracts and how they apply to the 12-18” rule, or how they apply in a best-case scenario. I still don’t think I would go with a multi-depth round like buck-and-ball or G2 RIP, but I can see the case being made for them.
I have to say that overall, it makes me question the effectiveness of a rifle over a shotgun or pistol round. It’s easy to say that they penetrate well and they have a giant PWC, but it’s also plain from most of the gel tests I’ve seen that in the “magic” 12-18” mark, most of the energy from the rifle round has been dumped and you’re left with the small remainder. Like I said, though, 30 in the box certainly helps make up for it.
