Thanks for the reminders.
Thanks for the reminders.
You can get much more of what you want with a kind word and a gun, than with a kind word alone.
im strong, i can run faster than train
Do you have evidence of this for the ammunition (subsonics) presently being discussed?
The reason I ask is that with lead core projectiles, defeating soft armor is a function of pressure dissipation rate (integrated with respect to time) that exceeds the longitudinal shock hugoniot of the aramid strand.
With slower projectiles that more readily deform against such resistance (RT in my prior post), impact force spread across a larger area due to projectile expansion reduces the magnitude of the pressure while concurrently lengthening the time frame of the pressure impulse reducing the strain rate and the likelihood that the aramid strand will fail under load.
''Politics is for the present, but an equation is for eternity.'' ―Albert Einstein
Full disclosure per the Pistol-Forum CoC: I am the author of Quantitative Ammunition Selection.
There’s a few videos out there showing penetration of lvl II vests. I also remember reading similar reports of heavy subsonic 762x39 being capable of the same back before .300BLK was a thing. Lvl III seems to stop it from the little research I’ve done.
Not a huge fan of MAC, testing starts around 7:00, also note the expanding leheigh(so) doesn’t penetrate.
im strong, i can run faster than train
Thanks for the links. Pretty much confirms my suspicions that anything greater that Level IIIa and higher will stop subsonic projectiles unless there's a hardened penetrator present in the projectile's construction. Not seeing Levels IIa and II as acceptable armor options (my preference personally is no less than IIIa) due to their lower resistance to higher energy (aka, velocity) threats, I tend to discount anything less than IIIa as an option. As alluded to a sentence or two ago, the presence of a hardened penetrator increases the likelihood that subsonic munitions might defeat heavier laminates by eliminating the reduction in the pressure interface balance brought about by deformation.
The "gold standard" in defeating thin targets composed of materials with high strain rate failure criteria is energy (velocity). This means that a greater return for investment from increasing velocity will be realized over that of increasing mass. It is possible to cause projectiles composed of softer materials to defeat targets made of harder materials than the projectile. This requires the use of extremely high speeds (called "critical velocity" by Alexseevskii & Tate, 1967) to drive the projectile fast enough to exceed the resistant pressure of the harder target material even in cases where the projectile might be treated as a 'zero-strength' jet.
I agree with your assessment about the capabilities of Level III armor in defeating subsonic projectiles.
Last edited by the Schwartz; 08-30-2020 at 12:13 PM.
''Politics is for the present, but an equation is for eternity.'' ―Albert Einstein
Full disclosure per the Pistol-Forum CoC: I am the author of Quantitative Ammunition Selection.
One of the things the Rooskies do with their 9x39 subsonic loads is use large and heavy steel penetrators in them.
While it’s hard to find confirmable open source info on effectiveness it’s interesting to note that they’ve been using these for going on 30 years now and they continue to issue the rifles and subsonic ammunition to folks going into harms way.
im strong, i can run faster than train
Like you're reading my mind, Senor Caballo.
The Soviets clearly paid attention to Alekseevskii's LRKEP research on both eroding and non-eroding penetrator performance when they designed their penetrators. Especially in the non-eroding/rigid penetration regime larger L/D ratios, < 3, translate to higher control volumes in the elastic/plastic field that forms ahead of the penetrator nose. These lengthier projectiles demand a large case volume behind them for obvious spatial issues (projectile impingement on propellant capacity, adequate gas volume to maintain pressure against expansion volume, etc.) , pistol caliber cases need not apply.
''Politics is for the present, but an equation is for eternity.'' ―Albert Einstein
Full disclosure per the Pistol-Forum CoC: I am the author of Quantitative Ammunition Selection.