Advantage of +P+ ammo

**john marston** · 15-09-2017, 17:23

Originally Posted by Quicksilver_WP

You are wrong. Or pretty much every 7.62x39 steelcore milsurp round currently being sold all over the country is illegal. Which do you think is more likely?

7.62x39 steelcore is not designated as "armour percing" even though it does indeed pierce some levels of body armour e.g level 1 level 2A level 2 and so fourth reason being that these are only designed to stop pistol calibre ammunition ... a 9mm fmj easily pierces level 1 body armour as this is only designed to stop .38 special rounds, by your logic this makes a 9mm fmj "armour percing".....i think ammunition has to meet certain requirements in its construction for it to be designated as being "armour percing" even though certain rounds such as the 7.62x39 that are not designated "armour percing" will out perform it.

**SSP** · 15-09-2017, 17:28

Originally Posted by Kayback

Are level III vests proof against THVs and the like?

I shot one of my THVs (9mmS version loaded in a 9X19 case running at 2600fps) into a level IIIA vest.

It went through both the front and back panel.

I did no hard armour testing though.

**Kayback** · 15-09-2017, 17:59

Originally Posted by SSP

I shot one of my THVs (9mmS version loaded in a 9X19 case running at 2600fps) into a level IIIA vest.

It went through both the front and back panel.

I did no hard armour testing though.

Yikes.

John Marston that is sorta Quicksilver's point. Most commercially available ammunition penetrate some armour or another. Most hunting rifles will burn through soft armour like it wasn't there and will defeat most rifle plates with enough hits.

Interestingly enough the new FBI standards for testing body-armour include contact shots as opposes to what it will stop with deformation minima. The muzzle blast helps destroy the integrity of the armour. So caliber and bullet construction isn't the only criteria any more

**john marston** · 15-09-2017, 18:16

Originally Posted by Kayback

Yikes.

John Marston that is sorta Quicksilver's point. Most commercially available ammunition penetrate some armour or another. Most hunting rifles will burn through soft armour like it wasn't there and will defeat most rifle plates with enough hits.

Interestingly enough the new FBI standards for testing body-armour include contact shots as opposes to what it will stop with deformation minima. The muzzle blast helps destroy the integrity of the armour. So caliber and bullet construction isn't the only criteria any more

I see, lol i guess the best policy would be to not get shot in the first place

**madhatter** · 15-09-2017, 18:21

Originally Posted by BigT

That thinking is long outdated

Massad wrote that in 2014
http://dailycaller.com/2014/06/25/massad-ayoob-downsizing-defense/

**BigT** · 15-09-2017, 20:17

Originally Posted by madhatter

Massad wrote that in 2014
http://dailycaller.com/2014/06/25/massad-ayoob-downsizing-defense/

Yup. He was out of sync with pretty much everyone else on that.

**madhatter** · 15-09-2017, 21:13

Dunno, he seems pretty experienced and still in the game to me.

**BigT** · 15-09-2017, 21:29

He's got funny ideas about Ammo. Has for years.

**Kayback** · 15-09-2017, 22:00

Some circles have said Mr Ayoob was good in the day but his time has past.

I personally have not read any Ayoob in about 10 years. He may still be cutting edge, but the people I have started following in the mean time don't follow his current teachings.

**Slamfire** · 05-10-2017, 05:36

A lot of the ideas rolling around in the gun writer community are untested. I think an analogy is would be nonsensical Euclidian geometry. You start with some postulates, that is things you assume are true but never tested, and you build proofs using them. In Euclidian geometry you prove the area of triangles, prove angles, etc with your postulates. All very elegant, all very top down.

I believe the +P and +P+ ideas were based around the gun writer concept that kinetic energy was related to stopping power. If your postulate is that “energy” is proportional to stopping power, than the more energy you put into a bullet, the better the stopping power. For me, momentum seemed to be the better measure of lethality, but these were all untested concepts. Anyway, if faster is better because KE= velocity squared times mass, then upping the pressure will certainly increase the velocity of the bullet, thereby increasing the lethality of the round, by the square of the velocity. Hence, +P must be better. Kinetic energy was easy to calculate, easy to promote in subscription magazines which are, simply advertising for the firearms industry.

Dr Martin Fackler conducted lethality testing and a crude summary of his work could be “the biggest through hole”. This was based on the idea that if something lives and breathes, if you make it bleed enough it will stop breathing, and hence, stop living. I think this has more validity than the old simple gunwriter models of kinetic energy. I remember reading that deer required a certain KE to kill, Elk, Moose took more, and Elephants, had to take much, much more KE to kill. These rules of lethality were quoted endlessly by the gunwriter community, it took on the aspect of fact, and that does influence readers who don’t know that none of it was ever verified by scientific testing.

The simplest way to increase KE is to increase velocity. That takes more pressure. But, I don’t consider pressure your friend. Things go bad faster the higher the pressure. Things wear out faster at higher pressures. If you can do the same job at a lower pressure, things will last longer and be more reliable. If you ever had malfunctions in hot weather, with ammunition developed in cooler weather, you have experienced one of the ways that pressure is not your friend.

Lethality is not a simple topic nor is it a settled science. But I am of the opinion that these higher pressure rounds were developed under the theory that faster was better, and that was based on the idea that KE was a measure of lethality.