small arm evolution and body armour

[Nemesis Lead]

Interesting charts--I have seen these before and there are a lot of different versions floating around the internet.

The M80 round has a very thick copper jacket. Instead of breaking apart, it tends to stay together and penetrate much deeper as the chart shows. Some of the 5.56mm rounds you have listed have very thin copper at the cannelure and tend to break apart into lots of fragments. Not much penetration, but more tissue damage. The Hornady and M118 7.62mm ammo is superior to the 5.56mm ammo (not sure if the former can be used by the military).

If you had looked at West German 7.62mm FMJ ammo, you would have seen a round that causes amazing damage. Very thin copper jacket that just "explodes" when it hits the target.

[luderbamsen]

Guys, we're drifting off topic, like. People have been debating terminal ballistics for ages, and this thread won't be the end of it

Since my comment (somewhat inadvertently) was drawn into this, allow me to clarify my point:

If any problems in defeating body armor with the 5.56x45mm round arises, the solution will likely be to issue 7.62x51mm weapons (rather than develop some fancy new weapon/caliber), since both weapons and ammo are readily availible. However, as long as there aren't any problems of this kind, the 5.56x45mm round will remain the standard caliber. For the foresseable future, that is.

[Barleyman]

The thing is, "they" want to shoot "you". And since "you" have body armor, "they" have a problem to overcome.

Since WP 7.62x39R ammo is not as powerful as NATO 7.62x51, there's no no-brainer solution for "red" force. Not that it was a good decision to use a full rifle cartridge for battle rifle..

Let's assume every nation looking forward for AP capability doesn't issue SVD as standard and AN-94 doesn't become supremely popular..

..On the other G3 is perfectly serviceable Battle rifle that's being produced in Iran and Pakistan among other places.

[acrashb]

Originally posted by luderbamsen:

If any problems in defeating body armor with the 5.56x45mm round arises, the solution will likely be to issue 7.62x51mm weapons

Here's the thing of it: soft armour doesn't stop 5.56, so no reason to switch. And SAPI plates stop up to 30-06 AP, so 7.62 doesn't cut it either... so you might as well stick to 5.56.

If full-coverage armour ever gets good enough to stop 5.56 (which it might, most likely through application of shear thickening fluids), the torso will still have added protection for 30-cal AP threats, so you have to go substantially past 7.62x61 to get results.

[acrashb]

Originally posted by tiny_tanker:

You also don't use a SMAW or 40mm to defeat a soldier in body armor.

Since we're talking small arms vs body armour ( I was thinking walls etc), you're right about SMAW. Maybe not re: 40mm although I doubt it's an approved use of the round.

I expect that body penetration is largely a function of energy density (coupled to ammo design, eg. stuff with internal penetrators and pointy tips), so that small rounds at high velocities (like with APFSDS tank rounds) will be the way forward in a body-armour-rich environment.

Then you have the issue of terminal ballistics - HK made /makes a small-diameter round (4.6mm? Don't recall) with a 'spoon tip' to improve the results of a hit. I've seen one - it looks weird but apparently works.

[luderbamsen]

Originally posted by acrashb:

</font><blockquote>quote:</font><hr />Originally posted by luderbamsen:

If any problems in defeating body armor with the 5.56x45mm round arises, the solution will likely be to issue 7.62x51mm weapons

Here's the thing of it: soft armour doesn't stop 5.56, so no reason to switch. And SAPI plates stop up to 30-06 AP, so 7.62 doesn't cut it either... so you might as well stick to 5.56.

If full-coverage armour ever gets good enough to stop 5.56 (which it might, most likely through application of shear thickening fluids), the torso will still have added protection for 30-cal AP threats, so you have to go substantially past 7.62x61 to get results. </font>

[The Warrior]

Originally posted by Cpl Steiner:

If the insurgents in Iraq or the Taliban in Afghanistan suddenly got a massive shipment of expensive and highly effective body armour tomorrow, what would the US military change about the way it fights the insurgents?

Answer: Probably very little. The US already relies on Apache helicopters and fixed-wing fighter-bombers to destroy its enemies once the fighting starts, and the sorts of weapons systems they employ are not bothered by a few mm of Kevlar.

By the way, did you know that the word "Taliban" means "seekers of knowledge" or "students". Quite ironic when you consider their favourite pastime seems to be the beheading of school teachers!

Yea but it's just those teachers that teach girls. :eek:

[ironbar]

As this discussion has focused almost exclusively on penetrating body armor, both soft and SAPI, I wonder if anyone has any insight into the parameters of a non-penetrating, debilitating hit. At some level blunt force trauma has to become a factor, if not spall from rigid armor. I wonder how much mass at what velocity it would take to put a troop in modern armor out of the fight; 12.7, 14.5? Or something like a .458 Magnum sporting round ?

[FAI]

Originally posted by ironbar:

As this discussion has focused almost exclusively on penetrating body armor, both soft and SAPI, I wonder if anyone has any insight into the parameters of a non-penetrating, debilitating hit. At some level blunt force trauma has to become a factor, if not spall from rigid armor. I wonder how much mass at what velocity it would take to put a troop in modern armor out of the fight; 12.7, 14.5? Or something like a .458 Magnum sporting round ?

12.7 or 14.5 will do...

[ November 21, 2007, 09:34 PM: Message edited by: FAI ]

[acrashb]

Originally posted by ironbar:

I wonder how much mass at what velocity it would take to put a troop in modern armor out of the fight; 12.7, 14.5? Or something like a .458 Magnum sporting round ?

12.7 and 14.5 will go clean through modern plates (level IV NIJ is rated to 30-06 AP).

If you envision a plate that would stop the rounds, then you look at how much momentum (mass x velocity) would be applied to a 10x12" surface ('standard' plate size) to put someone down for the count.

I have no idea what that would be. I have seen a video of a guy taking a Dragunov round in the chest, and getting up seconds later still in the fight (albeit with massive bruising), but that's not a really high-energy round.

[tiny_tanker]

Aren't troops only issued level 3 sapi plates?

I've seen that Dragunov video before, its amazing what adding a few more inches to an AK-47 barrel will do to muzzle velocity, add some AP rounds to the equation and your in a world of hurt. Though I think a few rounds from a 7.62, or 30-06 rifle would destroy a sapi plate.

[acrashb]

Originally posted by tiny_tanker:

Aren't troops only issued level 3 sapi plates?

I think the first SAPI plates were rated to 7.62AP (not directly comparable to the NIJ ratings or, again AFIAK, tested to those ratings). Current ('ESAPI') are rated similarly to NIJ IV.

Someone else will know for sure.

Edit: http://en.wikipedia.org/wiki/Interceptor_body_armor

[offtaskagain]

The first round of SAPIs were rated to 7.62x39 ball, not AP. The ESAPIs were fielded due to an incident in Al Qaim of several Marines being shot through the chest by 7.62x39 AP. If you've ever seen the documentary about the Marines of Lima Company this event is covered in there. ESAPIs, as those who have worn them know too well, are a good deal thicker and heavier and are rated to .30-06 AP. They do provide a pretty good deal of blunt force protection as well. A bit of late night jackassery by my friends and I revealed someone wearing them can take a full speed impact of an aluminum baseball bat to the chest without so much as flinching. I guess the impact just gets spread out over such a large area it doesn't affect them. I'll leave that energy equation to someone else.

[Barleyman]

Originally posted by tiny_tanker:

Aren't troops only issued level 3 sapi plates?

I've seen that Dragunov video before, its amazing what adding a few more inches to an AK-47 barrel will do to muzzle velocity, add some AP rounds to the equation and your in a world of hurt. Though I think a few rounds from a 7.62, or 30-06 rifle would destroy a sapi plate.

The fact that Dragunov fires 7.62x54R, not 7.62x39 may have something to do with the velocity as well..

[acrashb]

Originally posted by offtaskagain:

The first round of SAPIs were rated to 7.62x39 ball, not AP.[...]

Thanks for the 'inside scoop'.

[ironbar]

Would the force of a hit be distributed across the full area of the plate? considering a squarely centered hit. Or would the energy be centered on a smaller impact area, hence my question concerning spall.

[acrashb]

Originally posted by ironbar:

hence my question concerning spall.

There are two kinds of plates: those that are "standalone" and those that require armour under them.

On a standalone plate, there's some type of back-face liner to control spall. On the others, your underlying flexible armour is part of the spall management.

[JasonC]

ironbar - blunt trauma won't be pleasant, but the force involved tops out at the strength of recoil the shooter takes to his shoulder, pretty much. As long as you "catch" the round as broadly and softly (in space the force dissipates over and time of the event) as he "threw" it, it will bruise your chest only as much as his shoulder. Small arm bullets are dangerous because they pack that force into a tiny area and make actual holes in the body, not because they are massive blows. They can't be, or the shooter couldn't stand the force of delivering them.

As for the 7.62x39 vs 7.62x54 issue, as the man said, it isn't the barrel length. It is the cartridge length and the amount of powder behind the round, and therefore the muzzle energy. Full rifle rounds have 2-3 times the energy of carbine ammunition, and the AK-47 is carbine ammunition. The original purpose of the extra energy in full rifle ammo is to be accurate at 1000 yards through a flatter trajectory. But the same "full speed" also deals with body armor in the first third or half of that distance.

[acrashb]

Originally posted by JasonC:

it will bruise your chest only as much as his shoulder.

Most of your post is accurate (bullets can't knock people back like in the movies), but the bruising issue is off.

A bullet accelerates in, let's say, 14", then decelerates in maybe 1" when it hits your plate, so the force will be higher. As mentioned, the bruising from the 7.62x54R was significant. Have a look at the guy's chest in the upper-middle portion of the montage:

[Barleyman]

Originally posted by JasonC:

The original purpose of the extra energy in full rifle ammo is to be accurate at 1000 yards through a flatter trajectory. But the same "full speed" also deals with body armor in the first third or half of that distance.

Ahem. I do believe it's got more to do with the manufacturing tools becoming more sophisticated over time than anything else. Brown Bess shot was huge, .75 caliber.. If you look at the history of firearms, the rounds become smaller and smaller over time. it's easier to make big-ass .45 cal pistol round than 9mm round, never mind .22 cal..

Now hunting moose is hunting moose and hunting men is hunting men. First off, moose is a huge animal so unless you're going to pepper it from nose to tail, you want to do huge damage. Hence the big-ass soft-nosed rounds..

Shooting at men is a different ballgame, thought. Up until VERY RECENTLY people were unarmoured, so main concerns are that people

a) do not stay put while you machine-gun them down

shoot back

these days there's the problem of

c) the damn guys will pick themselves up a few moments after you shot them and dust themselves off!

That's the body armour bit. Still, .22 bullet is deadly, don't let the FPS kids fool you.

[flamingknives]

I was under the impression that the size of projectile was dependent on the efficiency of the propellant, along with the strength of the steel used to make the barrel. It's easy enough to make lead shot any size you like, but it isn't practical to propel them at any meaningfull velocities with gunpowder.

Machining capability comes into it a bit, because it is harder to manufacture a small calibre barrel to necessary tolerances. That, however, is the weapon, not the projectile.

[acrashb]

You might pickup a book on Interior Ballistics.

Anything around or under about .20 calibre fouls the barrel quickly - the faster you push the bullet, the more fouling. Also there are diminishing returns on packing more powder behind a bullet or putting more barrel in front of it.

[akd]

Originally posted by Barleyman:

</font><blockquote>quote:</font><hr />Originally posted by JasonC:

The original purpose of the extra energy in full rifle ammo is to be accurate at 1000 yards through a flatter trajectory. But the same "full speed" also deals with body armor in the first third or half of that distance.

Ahem. I do believe it's got more to do with the manufacturing tools becoming more sophisticated over time than anything else. Brown Bess shot was huge, .75 caliber.. If you look at the history of firearms, the rounds become smaller and smaller over time. it's easier to make big-ass .45 cal pistol round than 9mm round, never mind .22 cal..

</font>

[Nikki Mond]

Big changes in calibers are coming soon. Very soon. The 50 cal sniper round will be replaced by the .416 round. The smaller barrett round has farther range and accuracy than the barrett m82A. To a sniper range and accuracy wins.

For the assault rifle, the big problem is round energy being lost by common cover obstacles, such as doors, branches etc. 5.56mm may be good enough to kill but not after the enertia is taken out of it. 6.5mm will likely be the contender. A remington round. Lighter than the 7.62 but more punch (mass) than the 5.56.

[acrashb]

Originally posted by Nikki Mond:

6.5mm will likely be the contender. A remington round.

These two statements don't fit together. The Remington offering is 6.8mm.

So... where do you get this inside information from?