Thoughts about Liberty Civil Defense vs body armor.

[corneileous]

Just curious what your guy’s opinions is of this ammunition and its results against body armor. If this stuff penetrates that well and other than the possibility of feeding issues because it’s so light, why wouldn’t this make good personal defense ammunition?

For starters, I’m not interested in this ammunition because I’ve already tried it and wasn’t pleased with it because the only failure to eject I’ve ever had was while using this ammunition that was just the standard pressure version, not the plus P version in my full size Beretta PX4 storm 40.

There’s another video I found showing this ammo’s frangible action in synthetic ballistics gel and even though it only penetrated about 10 inches, I didn’t link it because I don’t think it’s relevant. I just thought it was quite interesting that this stuff went through body armor and would have been more interested in seeing the the results of ballistics gel behind the armor instead of a big ole chunk of what looks like modeling clay.

https://youtu.be/Nr6h44Pu4sM


Sent from my iPhone using Tapatalk

[the Schwartz]

Just curious what your guy’s opinions is of this ammunition and its results against body armor. If this stuff penetrates that well and other than the possibility of feeding issues because it’s so light, why wouldn’t this make good personal defense ammunition?

For starters, I’m not interested in this ammunition because I’ve already tried it and wasn’t pleased with it because the only failure to eject I’ve ever had was while using this ammunition that was just the standard pressure version, not the plus P version in my full size Beretta PX4 storm 40.

There’s another video I found showing this ammo’s frangible action in synthetic ballistics gel and even though it only penetrated about 10 inches, I didn’t link it because I don’t think it’s relevant. I just thought it was quite interesting that this stuff went through body armor and would have been more interested in seeing the the results of ballistics gel behind the armor instead of a big ole chunk of what looks like modeling clay.

https://youtu.be/Nr6h44Pu4sM


Sent from my iPhone using Tapatalk

I'd avoid the Liberty Civil Defense (in every caliber) for self-defense.

In unobstructed and clothing covered 10% ordnance gelatin, the Liberty Civil Defense 9mm 50-grain HP routinely sheds the resulting petals (due to expansion) within 4 inches of entering the gelatin block leaving the caliber-size cylindrical base to penetrate to a depth of 10 - 12 inches. In doing so, the base, which resembles a flat disk (or a shortened right cylinder) with ragged leading edges, typically turns sideways and penetrates in an 'edge on' attitude that produces an unremarkable permanent cavity that is much smaller than the diameter of the penetrating base (disk).

As for its ability to defeat a III-A soft armor insert, because the Liberty Civil Defense's copper alloy is both sufficiently hard and dense (about 8.85 g/cm³), if it remains rigid and can be pushed fast enough, it will defeat such barriers. All it needs to do to accomplish this is exceed the ''critical velocity'' (V_AT) of the armor substrate which is defined by Alekseevskii and Tate in their hydrodynamic pressure interface model as—



—where R_t is the dynamic resistance of the armor substrate which is governed by strain hardening, Y_p is the dynamic yield strength of the penetrator (sometimes taken as 1.7 times the yield strength of the penetrator material, and ρ_P is the density of the penetrator. The determination of R_t requires extremely complex computations since it is a velocity-dependent property and not a material constant. Sometimes, in much simpler armor penetration models, R_t is assumed to be 4.5 - 5.5 times the yield strength of the target material, but that approximation introduces considerable error when compared to actual test data.



Pick something off of Dr Roberts' list here—

https://pistol-forum.com/showthread....f-Defense-Ammo

—and you cannot go wrong.

[corneileous]

I'd avoid the Liberty Civil Defense (in every caliber) for self-defense.

In unobstructed and clothing covered 10% ordnance gelatin, the Liberty Civil Defense 9mm 50-grain HP routinely sheds the resulting petals (due to expansion) within 4 inches of entering the gelatin block leaving the caliber-size cylindrical base to penetrate to a depth of 10 - 12 inches. In doing so, the base, which resembles a flat disk (or a shortened right cylinder) with ragged leading edges, typically turns sideways and penetrates in an 'edge on' attitude that produces an unremarkable permanent cavity that is much smaller than the diameter of the penetrating base (disk).

Makes perfect sense.

As for its ability to defeat a III-A soft armor insert, because the Liberty Civil Defense's copper alloy is both sufficiently hard and dense (about 8.85 g/cm³), if it remains rigid and can be pushed fast enough, it will defeat such barriers. All it needs to do to accomplish this is exceed the ''critical velocity'' (V_AT) of the armor substrate which is defined by Alekseevskii and Tate in their hydrodynamic pressure interface model as—



—where R_t is the dynamic resistance of the armor substrate which is governed by strain hardening, Y_p is the dynamic yield strength of the penetrator (sometimes taken as 1.7 times the yield strength of the penetrator material, and ρ_P is the density of the penetrator. The determination of R_t requires extremely complex computations since it is a velocity-dependent property and not a material constant. Sometimes, in much simpler armor penetration models, R_t is assumed to be 4.5 - 5.5 times the yield strength of the target material, but that approximation introduces considerable error when compared to actual test data.

Not really sure I fully understand what you’re saying here. I mean, it kind of sounds like you’re saying this is a relatively soft body armor and that just because this round penetrated it, still doesn’t mean it’s all that lethal afterwards, considering it put quite the hole in that modeling clay after it went through the armor. Am I correct? Partially correct or not at all?…lol.

Pick something off of Dr Roberts' list here—

https://pistol-forum.com/showthread....f-Defense-Ammo

—and you cannot go wrong.

Oh yeah. I run 124-g Federal HST in my Compact 9mm Beretta Storm, 165-g Federal HST in my full-size Beretta Storm 40 and I run 230-g Speer Gold Dot in my full-size Beretta Storm 45 along with 230-g short-barrel Speer gold dot in my compact Springfield XDE 45 but speaking of which, being that a lot of those recommendations are +P, should I be running those instead of just standard pressure? I’m not sure if Speer or if even Federal has some short-barrel 45’s in +P but I just noticed that Speer also has a Gold Dot Carry Gun 45 Auto in a +P that’s 200-g for I’m assuming the same short-barreled 45’s like my XDE….


Sent from my iPhone using Tapatalk

[the Schwartz]

Makes perfect sense.
Not really sure I fully understand what you’re saying here. I mean, it kind of sounds like you’re saying this is a relatively soft body armor and that just because this round penetrated it, still doesn’t mean it’s all that lethal afterwards, considering it put quite the hole in that modeling clay after it went through the armor. Am I correct? Partially correct or not at all?…lol.

No, that's not at all what I was saying. I'll clarify...

When I made this comment—

As for its ability to defeat a III-A soft armor insert, because the Liberty Civil Defense's copper alloy is both sufficiently hard and dense (about 8.85 g/cm³), if it remains rigid and can be pushed fast enough, it will defeat such barriers. All it needs to do to accomplish this is exceed the ''critical velocity'' (V_AT) of the armor substrate which is defined by Alekseevskii and Tate in their hydrodynamic pressure interface model as—



—where R_t is the dynamic resistance of the armor substrate which is governed by strain hardening, Y_p is the dynamic yield strength of the penetrator (sometimes taken as 1.7 times the yield strength of the penetrator material, and ρ_P is the density of the penetrator. The determination of R_t requires extremely complex computations since it is a velocity-dependent property and not a material constant. Sometimes, in much simpler armor penetration models, R_t is assumed to be 4.5 - 5.5 times the yield strength of the target material, but that approximation introduces considerable error when compared to actual test data.

—all that it means (in simpler terms) is that if you push a projectile fast enough, even if the projectile is made of a material that has less strength than the target, there is a velocity at which the projectile will pass through the target material. It's residual velocity, or V_r, (which is how much speed it has left after passing through the target) depends upon its impact speed (V_i) and the V₅₀ (ballistic limit) of the target material and can be estimated through the relatively simple energy relationship of V_r = √[(V_i)² - (V₅₀)²]. Obviously, in the case of the video that you linked to, the 90-grain Liberty Civil Defense projectile had enough energy (velocity) to pass through the armor insert and leave a large impression in the clay block behind it.

Computations like these are usually made using the Alekseevskii-Tate hydrodynamic pressure interface model:

½ρ_P(V-U)² + Y_P = ½ρ_TU² + R_T

Y_P = projectile yield strength (Hugoniot Elastic Limit)
R_T = target resistive strength
ρ_P = projectile density
ρ_T = target density

The following transcendental equation, which can be solved to determine R_t in relationship to α to the density, shear (G_T) and bulk (K_T) moduli of the target material is—

[1 + (ρ_TU² ÷ Y_T) · √(K_T - ρ_Tα²U²)] = Y_T · [1 + (ρ_Tα²U² ÷ 2G_T) · √(K_T - ρ_TU²)].

Assuming a steady-state flow stress field in the target ahead of the projectile and setting 'm' as the slope of the intact yield strength/pressure curve (where m = ¾ for ductile targets) of the target material, solution of the transcendental equation for α is—

α = √[(2√3G_T) ÷ (2σ_yT + ½mρ_TU²)]

—where α must then be utilized in the computation of R_T —

R_T = (7 ÷ 3) · LN(α) · σ_yT

σ_yT = yield strength of the target material.

The Alekseevskii-Tate hydrodynamic pressure interface model is kind of a neat model because it allows us to do really interesting things like figure out how fast a .38 Special 158-grain FMJRN bullet would need to be pushed to defeat a 10mm thick piece of 500BHN armor plate.

Turns out that our .38 Special 158-grain FMJRN would need to strike the armor plate at 3,766 fps (V_AT) to do so, but when it exits the rear of the armor plate at ≈860 fps, almost all of its mass will have been consumed by erosion and it will exit as a small flat disc weighing just 1.3 grains with a 'length' of about 0.005''!

[corneileous]

No, that's not at all what I was saying. I'll clarify...

When I made this comment—



—all that it means (in simpler terms) is that if you push a projectile fast enough, even if the projectile is made of a material that has less strength than the target, there is a velocity at which the projectile will pass through the target material. It's residual velocity, or V_r, (which is how much speed it has left after passing through the target) depends upon its impact speed (V_i) and the V₅₀ (ballistic limit) of the target material and can be estimated through the relatively simple energy relationship of V_r = √[(V_i)² - (V₅₀)²]. Obviously, in the case of the video that you linked to, the 90-grain Liberty Civil Defense projectile had enough energy (velocity) to pass through the armor insert and leave a large impression in the clay block behind it.

Computations like these are usually made using the Alekseevskii-Tate hydrodynamic pressure interface model:

½ρ_P(V-U)² + Y_P = ½ρ_TU² + R_T

Y_P = projectile yield strength (Hugoniot Elastic Limit)
R_T = target resistive strength
ρ_P = projectile density
ρ_T = target density

The following transcendental equation, which can be solved to determine R_t in relationship to α to the density, shear (G_T) and bulk (K_T) moduli of the target material is—

[1 + (ρ_TU² ÷ Y_T) · √(K_T - ρ_Tα²U²)] = Y_T · [1 + (ρ_Tα²U² ÷ 2G_T) · √(K_T - ρ_TU²)].

Assuming a steady-state flow stress field in the target ahead of the projectile and setting 'm' as the slope of the intact yield strength/pressure curve (where m = ¾ for ductile targets) of the target material, solution of the transcendental equation for α is—

α = √[(2√3G_T) ÷ (2σ_yT + ½mρ_TU²)]

—where α must then be utilized in the computation of R_T —

R_T = (7 ÷ 3) · LN(α) · σ_yT

σ_yT = yield strength of the target material.

The Alekseevskii-Tate hydrodynamic pressure interface model is kind of a neat model because it allows us to do really interesting things like figure out how fast a .38 Special 158-grain FMJRN bullet would need to be pushed to defeat a 10mm thick piece of 500BHN armor plate.

Turns out that our .38 Special 158-grain FMJRN would need to strike the armor plate at 3,766 fps (V_AT) to do so, but when it exits the rear of the armor plate at ≈860 fps, almost all of its mass will have been consumed by erosion and it will exit as a small flat disc weighing just 1.3 grains with a 'length' of about 0.005''!

Man, I really wish I woulda paid more attention in Algebra class but math never was one of my strong suits…lol.

So then in layman’s terms, why is this ammo not a good choice even though it will penetrate armor? I realize that one little piece that’s the size of a small watch battery is all that remained but it still looked pretty lethal to me if the target wasn’t wearing body armor.

Sorry if I’m not getting what you’re saying. You’re speaking way above my education level….lol.


Sent from my iPhone using Tapatalk

[JCN]

Turns out that our .38 Special 158-grain FMJRN would need to strike the armor plate at 3,766 fps (V_AT) to do so, but when it exits the rear of the armor plate at ≈860 fps, almost all of its mass will have been consumed by erosion and it will exit as a small flat disc weighing just 1.3 grains with a 'length' of about 0.005''!

That. Is. Awesome!

I visually pictured what that would look like in my mind’s eye and it was glorious!

[the Schwartz]

Man, I really wish I woulda paid more attention in Algebra class but math never was one of my strong suits…lol.

So then in layman’s terms, why is this ammo not a good choice even though it will penetrate armor? I realize that one little piece that’s the size of a small watch battery is all that remained but it still looked pretty lethal to me if the target wasn’t wearing body armor.

Sorry if I’m not getting what you’re saying. You’re speaking way above my education level….lol.

No problem.

Even though the Liberty Civil Defense does penetrate some armors, it's not a particularly good choice for self-defense because after it does so, it...

...typically turns sideways and penetrates in an 'edge on' attitude that produces an unremarkable permanent cavity that is much smaller than the diameter of the penetrating base (disk).

Dr. Roberts' ammunition recommendations https://pistol-forum.com/showthread....f-Defense-Ammo offer superior expanded diameter and penetration depth which results in increased soft tissue damage of the CNS and large vascular structures needed to produce rapid involuntary incapacitation.

While 'quantity' (how much tissue is damaged) certainly matters, 'quality' (the type of tissue damaged) matters even more.

[the Schwartz]

That. Is. Awesome!

I visually pictured what that would look like in my mind’s eye and it was glorious!

Did it look a little like this?

[JCN]

Did it look a little like this?

Kind of halfway between that and this:

[corneileous]

No problem.

Even though the Liberty Civil Defense does penetrate some armors, it's not a particularly good choice for self-defense because after it does so, it...



Dr. Roberts' ammunition recommendations https://pistol-forum.com/showthread....f-Defense-Ammo offer superior expanded diameter and penetration depth which results in increased soft tissue damage of the CNS and large vascular structures needed to produce rapid involuntary incapacitation.

While 'quantity' (how much tissue is damaged) certainly matters, 'quality' (the type of tissue damaged) matters even more.

So then aside from having to penetrate body armor; what’s wrong with it in that situation?


Sent from my iPhone using Tapatalk