AR15 or AK47 ?

[Duces Tecum]

I just read this the other day, and I thought it was interesting.

Thank you! Most interesting.

[Default.mp3]

I just read this the other day, and I thought it was interesting.

Why I'd rather be shot with an AK47 than an M4.

Except that writer places a large emphasis on the temporary cavitation generated by the 5.56×45mm as being the primary reason it has superior wound ballistics compared to the 7.62×39mm:

Far more damaging than the permanent cavity left by a projectile is the temporary cavity that it creates. Anyone who has ever watched the TV show Myth Busters will have some familiarity with this concept, and it is best demonstrated using slow motion video imagery of bullets being shot into special jelly known as ballistic gelatin, which is calibrated to be the same density as human soft tissues. What can be seen in these video images is the pulsating dissipation of energy that emanates out from a bullet as it passes through the gelatin. This is a visual illustration of the concept of temporary cavitation, and it allows the viewer to begin to appreciate the devastating effect that a high velocity missile can have once it enters a human body. The temporary cavitation is the transfer of Kinetic Energy from the projectile into the tissues of the target, and as we learned above, is relative to the mass and, more importantly, the velocity of the projectile. As the energy of the projectile is dissipated into the tissues of the target the temporary cavitation pulverizes structures adjacent to the bullet’s tract, including blood vessels, nerves, muscles and any solid organs that may be in close proximity. For that reason the high velocity projectile does not need to pass directly through a structure in the body to destroy it. The higher the Kinetic Energy of the projectile the further out from the permanent cavity the temporary cavity extends.

Emphasis mine.

Yet DocGKR states that:

The tissue surrounding the permanent cavity is briefly pushed laterally aside as it is centrifugally driven radially outward by the projectile's passage. The empty space normally occupied by the momentarily displaced tissue surrounding the wound track, is called the temporary cavity. The temporary cavity quickly subsides as the elastic recoil of the stretched tissue returns it towards the wound track. The tissue that was stretched by the temporary cavity may be injured and is analogous to an area of blunt trauma surrounding the permanent crush cavity. The degree of injury produced by temporary cavitation is quite variable, erratic, and highly dependent on anatomic and physiologic considerations. Many flexible, elastic soft tissues such as muscle, bowel wall, skin, blood vessels, and empty hollow organs are good energy absorbers and are highly resistant to the blunt trauma and contusion caused by the stretch of temporary cavitation. Inelastic tissues such as the liver, kidney, spleen, pancreas, brain, and completely full fluid or gas filled hollow organs, such as the bladder, are highly susceptible to severe permanent splitting, tearing, and rupture due to temporary cavitation insults. Projectiles are traveling at their maximum velocity when they initially strike and then slow as they travel through tissue. In spite of this, the maximum temporary cavity is not always found at the surface where the projectile is at its highest velocity, but often deeper in the tissue after it has slowed considerably. The maximum temporary cavitation is usually coincidental with that of maximum bullet yaw, deformation, or fragmentation, but not necessarily maximum projectile velocity.

...

Projectile fragmentation in tissue can also greatly increase the permanent cavity size. When a rifle bullet fragments in tissue, each of the multiple fragments spreads out radially from the main wound track, cutting its own path through tissue. This fragmentation acts synergistically with the stretch of temporary cavitation. The multiply perforated tissue loses its elasticity and is unable to absorb stretching that would ordinarily be tolerated by intact tissue. The temporary cavitation displacement of tissue, which occurs following the passage of the projectile, stretches this weakened tissue and can grossly disrupt its integrity, tearing and detaching pieces of tissue. Note that handgun bullets, regardless of whether they are fired from pistols or SMG’s, do not generally exhibit the fragmentation effects produced by rifle bullets. If handgun bullets do fragment, the bullet fragments are usually found within 1 cm of the permanent cavity; wound severity is usually decreased by the fragmentation since the bullet mass is reduced, causing a smaller permanent crush cavity.

Emphasis mine.

Source: https://pistol-forum.com/showthread....formance-Facts

So, yes, temporary cavitation can play an important role in the efficacy of rifle ammunition... but I don't think it plays the overwhelming role that Mr. Pronk seems to think it does in this little case study.

[texasaggie2005]

...

I'd agree with that. Whenever I see temp or perm cavity discussions, I tend to just gloss over it, since it's typically bad info anyways, as you pointed out with ref to DocGKR's post.

Had the example 7.62x39 bullet hit bone, I imagine the damage would have more severe than the ice pick it did. I hate to even bring this up as an example, but Tom's wife is an excellent example that an AK round can certainly cause extensive damage when hitting bone.

[Chuck Haggard]

For the most part the x39 doesn't have many loads that make either a permanent or temp cavity large enough to exceed the performance of the 5.56 round. All of the various non-expanding loads that fail to yaw exhibit wounding about the same as the old .38 RNL standard velocity bullet.

Check out the last diagram in the thread;
https://pistol-forum.com/showthread....listic-History


Something like the Hornady SST loading can more mimic the 30-30 in wounding. That still doesn't make this a .22lr vs .45acp argument in nature. The 5.56 in any .mil load that yaws, or expanding/fragmenting load with a 55gr or greater bullet typically knocks the shit out of people at close range.

In rifles temp cavity IS a thing.

[Hizzie]

I just read this the other day, and I thought it was interesting.

Why I'd rather be shot with an AK47 than an M4.

Apples to cabbages. Guy compares a 556 to the femur vs a 762 to just meat.

[Flintsky]

Logistically, AR-15 if you are in the United States. If I were in Russia, I would go with a AK-74 variant. Quality and support is almost always best for a weapon system in their country of origin.