Firepower and Ballistics - Sten Gun 9mm vs. Thompson .45 ACP

[flamingknives]

I've been seemingly knocked flat by nothing more powerful than a paintball. Point is I spotted the shooter just before he fired and threw myself backwards. To an observer, however, someone started shooting and I flew (fell over would probably be more accurate) backwards.

Newtonian mechanics means that if a bullet can knock a man down, then the recoil forces must also apply that force to the shooter. That assumes that all the power in the bullet is transferred to the target, which isn't always the case.

[Kozure]

Originally posted by flamingknives:

I've been seemingly knocked flat by nothing more powerful than a paintball. Point is I spotted the shooter just before he fired and threw myself backwards. To an observer, however, someone started shooting and I flew (fell over would probably be more accurate) backwards.

Newtonian mechanics means that if a bullet can knock a man down, then the recoil forces must also apply that force to the shooter. That assumes that all the power in the bullet is transferred to the target, which isn't always the case.

This theoretical example doesn't necessarily take into account that the firer is usually braced and prepared for the impact of the recoil, while the target may be in motion or otherwise off balance.

Here's an easy (hypothetical) test. Have a (trusting) friend stand stationary and braced within arm reach. Give him a good kick in the leg. Odds are he won't fall down, or if he does, he'll just sort of crumple slowly.

Now, have him walk by you. As he passes, kick him with the same amount of force in the leg which is carrying weight at the time. He'll probably collapse and if momentum is enough, appear to be knocked over. Repeat tests on various parts of his body.

The demonstration on the myth of "knockdown power" was quite striking (pun unintended): a man in a heavy ballistic vest balanced on one foot while another man shot him in the chest with a FN-FAL from three feet away (the FN-FAL is a full-power .30 cal rifle, roughly on a par with an M1 in terms of "BANG!"). The target guy flinched, but didn't even wobble. He certainly didn't fall over (and remember, he was balancing on one foot).

This test distorts the situation somewhat, as a great deal of the effectiveness of a ballistic vest is its ability to distribute the impact energy (via ballistic cloth) over the surface of the impact area and over the vest as a unit.

One factor which is almost always lost in theoretical testing is the myriad of outside factors and situational modifiers which affect the results of field situations.

Sometimes people got killed by shell fragments which were no larger than fingernails. Other times the body was completely intact, having been killed by overpressure or simple shock/fright. Conversely, men have gone on fighting when by all rights they should be dead, bleeding from a dozen wounds.

Similarly a shot which knocks one man down might in another situation leave him standing. The bullet may tumble, hydrostatic shock may cause effects secondary to the actual wound path, it may glance off a bone or cut an artery cleanly. What a bullet does inside a body cannot be predicted with any amount of certainty.

The bullet must pass through the large, blood bearing organs and be of sufficient diameter to promote rapid bleeding.

Not necessarily true. Hydrostatic shock can cause damage at quite a distance from the direct wound path. In addition, energy transfer effects can be altered by changing the way the bullet breaks up in the body (hollowpoint or glaser rounds) or remains more intact (AP or FMJ rounds) there are so many factors affecting the way that a projectile can wound and injure a body, it's quite a challenge to outright dismiss one effect versus another.

I think it can be safely said that a bullet impacting a body can in many cases cause a man to fall down or backwards, appearing to have been "knocked down".

I think it can also said with a fair amount of agreement that a 9mm Parabellum round fired from a stable firing platform has better ballistic performance (range) and penetration capacity, while at the same time being less likely to "stop" a target while the .45 ACP has a higher bullet mass and a larger calibre which results in higher transfer of energy at short ranges and a larger wound path. This is consistent with the .45 ACP rounds' development as a "man-stopper" weapon for use against insurgents in the Phillipines. (insert standard disclaimer about myth-making and the Moro rebels, plus religious/racial stereotyping/exaggeration in first hand accounts of the time). The Sten, being a relatively unstable platform due to its weight and construction, was not necessarily as effetive in many situations.

From these points, we can say that the Thompson has a higher FP rating in CM because it is: more accurate, has a higher rate of sustainable automatic fire and has greater "stopping power"

[flamingknives]

This theoretical example doesn't necessarily take into account that the firer is usually braced and prepared for the impact of the recoil, while the target may be in motion or otherwise off balance.

No, but it wasn't intended to. The point is that a bullet has no more kinetic energy than the recoil energy. It might give an extra tip to an already off balance person, but it won't stop someone coming at you or knock over someone standing still

Regards ballistic vests. If anything, they will increase the force applied to the target, as the bullet is entirely stopped in a shorter distance. Some of the energy will be taken up by stretching of the ballistic fibres, but the bullet is stopped, whereas a 7.62 full power round would usually go straight through.

Otherwise, agreed.

[DevilDog]

The reason that 45ACP wins over 9mm with regard to stopping power is related to penetration. While the .45 round is much heavier, the 9mm has a higher velocity, which contributes more to the kinetic enegry than the weight. However, 9mm rounds often suffer from overpenetration, which means that a large portion of their kinetic energy is not absorbed by the target. In other words, the effect of a round with higher kinetic energy which overpenetrates will usually be less than a lower energy round which imparts its entire energy to the target (i.e. plastic collision, or the round stays in the target).

A .45 round has less velocity and a larger cross-section, which means that it will not penetrate nearly as much as a 9mm, but at the same time usually guaratees that the full kinetic energy from the .45 bullet will be absorbed by the target.

Now which you prefer is a matter of preference and use. A 9mm would be much better suited for shooting at someone with some type of body armor on (even if the vest stops the rounds, the shock can still kill the victim), while for law enforcement situations, the .45 would be preferable over the 9mm because there is a lower chance for overpenetrations injuring innocent people.

I personally prefer and own a .45 handgun.

[ January 21, 2004, 12:19 PM: Message edited by: DevilDog ]

[Eric Alkema]

That makes sense if it is kinetic energy that puts a man down. It didn't put down the guy in the body armor. If the idea is to put as big a hole in the target as possible, the overpenetrating shot made as deep a hole as possible. I guess whether or not that makes up for having a slightly smaller cross section depends on how far the .45 penetrates.

[Fluf]

I find the story about the man in body armour taking a 7.62 NATO round at point blank range and shrugging it off hard to believe, unless it was a softpoint or rubber bullet or something. Those solid point military rounds (7.62 NATO = Winchester .308) penetrate 4 inches of steel plate at point blank. I've observed the large chunks of turf that they toss way up in the air when they hit the ground in front of the target butts (not from MY shooting of course :cool: ).

[Kozure]

Originally posted by Fluf:

I find the story about the man in body armour taking a 7.62 NATO round at point blank range and shrugging it off hard to believe, unless it was a softpoint or rubber bullet or something. Those solid point military rounds (7.62 NATO = Winchester .308) penetrate 4 inches of steel plate at point blank. I've observed the large chunks of turf that they toss way up in the air when they hit the ground in front of the target butts (not from MY shooting of course :cool: ).

The really, really heavy ballistic vests can apparently stop 7.62mm ammo, but the wearer looks like the Stay-Puft marshmallow man, and isn't practical for field use.

I'm also a little incredulous at the idea of shooting a FAL at point blank at a guy balancing on one foot... but hey... stranger things happen.

I think that among the other horrendous misconceptions that Hollywood has foisted on us is that your standard slimline or even military issue vest can stop rifle rounds. I don't know how many times I've seen the ol' "Oh look he's been shot but no wait he's okay he pulled open his shirt and he's got a vest on." trick on TV.

Buncha hooey.

I think things were easier to explain when they were called flak vests, rather than bulletproof vests. They're supposed to stop fragments and glancing, spent-energy rounds, not direct, short range rifle hits!

Meh... preaching to the choir here. Everyone here seems to be in thunderous agreement except about "knockdown" effects.

[flamingknives]

12mm RHA will stop a 7.62x51mm AP round - even a .50cal won't go through 4".

With the ceramic inserts modern body armour, as issued to well kitted out infantry, will stop a kalashnikov round (7.62x39mm)

The important thing to remember is that it won't do it twice

[JasonC]

One fellow mentioned hydrostatic shock. It is not an issue with pistol ammo, certainly not WW II pistol ammo. A full rifle or true MG round, with 3000+ Joules remaining even at range, might produce extra wound effects that way. But 45 rounds are going very very slow for a bullet. The 9mm rounds used in WW II aren't going much faster (modern high power 9mm ammo goes a lot faster, but still doesn't reach the energy of a carbine round let alone a rifle round).

High velocity - rifle rather than pistol ammo - is not of great importance for wounding, though it generally will ensure complete penetration. It matters most for accuracy at range. Pistol ammo drops so much because it is going so slow, and that makes it hard to hit anything beyond 100 yards.

None of them are going to knock people about. Rifle rounds because they go through and so deposit only a fraction of their high energy, pistol rounds because they don't have much energy in the first place. Pistol ammo might occasionally underpenetrate e.g. not go through bone, and so leave only a shallow wound sometimes.

Sometimes any kind of round will go through but not hit anything vital - leaving a painful arm or leg wound e.g., but not incapacitating. There is a reason wounds outnumber deaths by 3 to 1 in WW II returns. In later wars for the side with improved medical attention, that can rise as high as 7 to 1.

But none of this is of much tactical significance. Men shot by a rifle or MG, or hit by several pistol caliber rounds from an SMG, are quite unlikely to continue fighting very effectively or for very long. They are losing blood rapidly, and often go into shock. If they attend to their wounds their survival chances are often excellent, though frequently they need help from others even to do that. They have been given urgent things to do, besides try to annoy the enemy.

[Los]

"The really, really heavy ballistic vests can apparently stop 7.62mm ammo, but the wearer looks like the Stay-Puft marshmallow man, and isn't practical for field use."

B.S. Our interceptor armor w/ trauma plate (Makes it level IV) has stopped numerous 7.62 rounds in both Afghanistan and Iraq. In fact in both areas soldiers felt a lot more confident in "trolling for contact" (AAR quotes) in their interceptors. One can manuever in the vest and it doesn't look like a "stay-puft" man. You are perfectly manueverable in the vest, in fact many have taken to shucking off LCE or web gear completely and attaching the molle ammo pouches and accessories directly to their interceptors. They're pretty much standard equipment now. If you have access to Center for Army lessons learned you can read extensive AAR reviews on the interceptor and accounts of the interceptor in combat. in AFghanistan, one guy in our battalion took two 7.62 rounds in an ambush, got up hopped over a stone wall, and killed both assailants on the other side.

Other than that you are correct, unless you have a trauma plate in your concealed wear "second chance" or "point blank" vest it's only good for 9mm, but then again that's better than nothing.

Los

[flamingknives]

7.62x51mm NATO, 7.62x39mm Kalashnikov or 7.62x54R (RPK and Draganov)?

[Kozure]

Originally posted by Los:

"The really, really heavy ballistic vests can apparently stop 7.62mm ammo, but the wearer looks like the Stay-Puft marshmallow man, and isn't practical for field use."

B.S. Our interceptor armor w/ trauma plate (Makes it level IV) has stopped numerous 7.62 rounds in both Afghanistan and Iraq. In fact in both areas soldiers felt a lot more confident in "trolling for contact" (AAR quotes) in their interceptors. One can manuever in the vest and it doesn't look like a "stay-puft" man. You are perfectly manueverable in the vest, in fact many have taken to shucking off LCE or web gear completely and attaching the molle ammo pouches and accessories directly to their interceptors. They're pretty much standard equipment now. If you have access to Center for Army lessons learned you can read extensive AAR reviews on the interceptor and accounts of the interceptor in combat. in AFghanistan, one guy in our battalion took two 7.62 rounds in an ambush, got up hopped over a stone wall, and killed both assailants on the other side.

Other than that you are correct, unless you have a trauma plate in your concealed wear "second chance" or "point blank" vest it's only good for 9mm, but then again that's better than nothing.

Los

I stand corrected. I am not familiar with the "interceptor armour with trauma insert". My understanding of ballistic armour is therefore altered considerably.

It had been my understanding that, at least until the late 1990s, most practical combat armour would not stop a 7.62mm at short range. Since that is no longer the case, I bow to your more recent knowledge.

*suitably chastised*

[John Kettler]

Kozure,

The .45 caliber's reputation as a manstopper in the Philippines against the Moros derives not from the

.45 ACP but the .45 Long Colt cartridge, an entirely different, longer, and much more powerful animal. Think Old West six shooter. What the Moro campaign did show was that the issue .38 revolvers simply couldn't get the job done, especially against fanatical troops who were also hopped up. The inadequacy of the .38 was also clearly evident in police work, where many examples exist showing they weren't powerful enough. I know of one case where a crook was shot in the forehead and the bullet didn't even break bone, but instead slid around under the skin and exited the back. The .38 also failed often when fired into windshields, rear windows, etc. Pretty depressing when trying to a) avoid being run down or stop a fleeing suspect.

Hope this helps shed a little light.

Regards,

John Kettler

[Kozure]

Originally posted by John Kettler:

Kozure,

The .45 caliber's reputation as a manstopper in the Philippines against the Moros derives not from the

.45 ACP but the .45 Long Colt cartridge, an entirely different, longer, and much more powerful animal. Think Old West six shooter. What the Moro campaign did show was that the issue .38 revolvers simply couldn't get the job done, especially against fanatical troops who were also hopped up. The inadequacy of the .38 was also clearly evident in police work, where many examples exist showing they weren't powerful enough. I know of one case where a crook was shot in the forehead and the bullet didn't even break bone, but instead slid around under the skin and exited the back. The .38 also failed often when fired into windshields, rear windows, etc. Pretty depressing when trying to a) avoid being run down or stop a fleeing suspect.

Hope this helps shed a little light.

Regards,

John Kettler

Hmmm... in my readings, it was indicated that the .45 ACP was developed out of the findings of the .38's ineffectiveness. I guess what I should have been clearer indicating that the .45 ACP as developed had to take into account the lessons learned in the Phillipines, not that the .45 acquired its reputation by being used in the Phillipines.

[Grey Hunter]

Look, there is only one way to solve this.

half of you get Stens, the other half tompsons, go into the woods and do some "field" research, rember to set up cameras so we can check for flying bodies.

hmm, this could be a new TV show - "when Debates go wrong"

[Jarmo]

Originally posted by John Kettler:

The .45 caliber's reputation as a manstopper in the Philippines against the Moros derives not from the

.45 ACP but the .45 Long Colt cartridge, an entirely different, longer, and much more powerful animal. Think Old West six shooter.

Does anyone have a link to the velocities, weights, energies of various shots? I was always under impression that .45 ACP is more effective than the "old west 45".