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Thread: 300blk - Subsonic in Rattler "outperforms" BCM 9in

  1. #51
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  2. #52
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    Quote Originally Posted by Sensei View Post
    Finally, subs in the 300blk. Is there any doubt that loading the Rattler with subs is going to give it something less than 9mm PCC performance? If people accept that premise, is the answer to always make head shots? I ask because that is what I seem to be reading.
    I’m not saying this should or should not be a driving factor on ammo selection, but an interesting effect of a long pointy bullet with good sectional density is that they’re capable of penetrating soft armor that will stop handgun rounds, even at subsonic velocities.
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  3. #53
    Quote Originally Posted by Caballoflaco View Post
    I’m not saying this should or should not be a driving factor on ammo selection, but an interesting effect of a long pointy bullet with good sectional density is that they’re capable of penetrating soft armor that will stop handgun rounds, even at subsonic velocities.
    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.
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  4. #54
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    Quote Originally Posted by the Schwartz View Post
    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.
    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.
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  5. #55
    Quote Originally Posted by Caballoflaco View Post
    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.
    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.

  6. #56
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    One of the things the Rooskies do with their 9x39 subsonic loads is use large and heavy steel penetrators in them.

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    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.
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  7. #57
    Quote Originally Posted by Caballoflaco View Post
    One of the things the Rooskies do with their 9x39 subsonic loads is use large and heavy steel penetrators in them.

    Name:  A14BE062-C715-4468-893C-C4F4B3B63380.jpeg
Views: 457
Size:  61.2 KB

    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.
    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.

  8. #58
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    Quote Originally Posted by Sensei View Post
    I think this is pretty much spot on.


    What follows is not directed at HCM. Honestly, I get confused by these threads. Perhaps the 110 Barnes will expand out to roughly 175-225 yards. But to what ends? To those encouraged that it expands beyond 175 yards, keep in mind you will have a 110 grain, .30 caliber bullet traveling at 1350-1450 fps. So, what do you expect it to expand to, exactly? Penetrating to what depth? Also, has anyone independently verified these expansion thresholds at sub-rifle velocities?

    My suspicion is that it will produce a wound profile that looks something less than what a 115 grain +P 9mm JHP produces - shallow and no temporary cavity to write home about. Most consider that to be less than ideal. So, I stopped trying to make my Rattler be all things. That means I don’t have a LPVO on my 5” rifle to account for the 2 foot drop at 250 yards. Mine is set up to engage 2 legged critters out to about 50 yards max. At that distance, I have no holdovers and still get some temporary cavitation. If I need to engage targets beyond 50 yards, I’m using something that still behaves like a rifle at that distance (9” 300blk, 11.5-14.5” 556, 762x39, 338LM, 50BMG, etc.

    Attachment 59562

    Finally, subs in the 300blk. Is there any doubt that loading the Rattler with subs is going to give it something less than 9mm PCC performance? If people accept that premise, is the answer to always make head shots? I ask because that is what I seem to be reading.
    I think you are spot in. Like the 300 BO round, the Rattler is a niche item. It’s good at what it does but if it was the do all wonderkind some make it out to be full size guns would not exist.

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