Re: Terminal effects of 5.56
After following this thread for a bit and re-reading this I will add a few points:
After it has been pointed out by some....Lets all get on the same page. The "tumbling" of a bullet people refer to occurs after impacting a semi-solid target. It occurs with nearly all projectiles, more so with longer projectiles with uneven weight distribution. It occurs because the majority of the mass of the round is in the base, which has more inertia and will continue forward while the nose will slow faster. Throw anything with weight in the ass end and watch how it turns eventually. This yawing or tumbling causes the permanent wound channel to be wider and thus do more damage. For some rounds, like the original 55gr 5.56 military round, this turning of the projectile while in tissue results in fragmentation of the projectile without striking bone or other hard object. This is a combination of the thin jacket, cannelure, and speed of impact of the round. Fragmentation causes significantly greater tissue damage and makes our job a whole lot harder. The stress is just too great on the bullet when moving sideways through tissue. Non-military bullets can be designed to expand and/or fragment without significant tumbling, but Geneva convention military rounds can not. If you slow a 5.56 nato projectile it will not be subjected to enough sheer force when yawing and will not reliably fragment without hitting bone. This is the problem with short barrels. Less muzzle velocity, shorter effective range for fragmentation. It then becomes a glorified 22mag. However, tunmbling and fragmentation is not limited to the 5.56 nato 55gr. There was a west german 7.62 nato projectile manufactured for some time that would reliably yaw and fragment upon impact with soft tissue. This was an unintentional byproduct of a deep cannalure, a thin jacket, and the shape of the projectile. Not all 7.60 rounds do this. This one did...and it was hell. Other 7.62 rounds will yaw and tumble, but without fragmentation they do not produce nearly as much damage. The AK round will tumble, but usually remains intact in soft tissue.
These debates often diverge into 2 directions/needs. The milatary is bound by Geneva rules and must use FMJ rounds not deliberately designed to expand or fragment. In that world, if you slow the 55gr nato round, you end up with less devastating wound channels. To increase terminal effects, you can restore velocity, increase weight, or increase diameter (caliber). Since fragmentation has to be a happy accident, you can't (in the open) plan for it. Civilian enthusiasts and police agencies can select 5.56 rounds which use projectiles designed to expand or better yet fragment at velocities much below the military threshold. This restores much of the 5.56's lethality. We have to be careful to separate the 2 arguements when discussing 5.56/223 terminal effects.
Just some food for thought. Of course, shot placement is king. This has been said before. Also, individual people vary. Some die from damn near nothing, others walk through walls. That being said.... I would not want to have to defend myself with a slow moving 5.56 nato round. However, I DO enter houses with non-military fragmenting/exapanding rounds from short barreled ARs without worry. Move that out 300 yards, however, and I am not so comfortable. If a round will only tumble and not fragment, I do feel better with 7.62 heading towards the bad guy.
For those who are interested, I work in an arena where even when there is a war on, we still help train PJs and other military spec ops medics how to deal with bullet wounds because our experience is pretty darn extensive. They have us on blast, but we hold our own with penetrating trauma. I am also a fully entry qual'd TacMed provider who employs what I talk about. I'm not overseas, but I have gathered nearly a decade of pretty directed experience on the subject.
Sean
After following this thread for a bit and re-reading this I will add a few points:
After it has been pointed out by some....Lets all get on the same page. The "tumbling" of a bullet people refer to occurs after impacting a semi-solid target. It occurs with nearly all projectiles, more so with longer projectiles with uneven weight distribution. It occurs because the majority of the mass of the round is in the base, which has more inertia and will continue forward while the nose will slow faster. Throw anything with weight in the ass end and watch how it turns eventually. This yawing or tumbling causes the permanent wound channel to be wider and thus do more damage. For some rounds, like the original 55gr 5.56 military round, this turning of the projectile while in tissue results in fragmentation of the projectile without striking bone or other hard object. This is a combination of the thin jacket, cannelure, and speed of impact of the round. Fragmentation causes significantly greater tissue damage and makes our job a whole lot harder. The stress is just too great on the bullet when moving sideways through tissue. Non-military bullets can be designed to expand and/or fragment without significant tumbling, but Geneva convention military rounds can not. If you slow a 5.56 nato projectile it will not be subjected to enough sheer force when yawing and will not reliably fragment without hitting bone. This is the problem with short barrels. Less muzzle velocity, shorter effective range for fragmentation. It then becomes a glorified 22mag. However, tunmbling and fragmentation is not limited to the 5.56 nato 55gr. There was a west german 7.62 nato projectile manufactured for some time that would reliably yaw and fragment upon impact with soft tissue. This was an unintentional byproduct of a deep cannalure, a thin jacket, and the shape of the projectile. Not all 7.60 rounds do this. This one did...and it was hell. Other 7.62 rounds will yaw and tumble, but without fragmentation they do not produce nearly as much damage. The AK round will tumble, but usually remains intact in soft tissue.
These debates often diverge into 2 directions/needs. The milatary is bound by Geneva rules and must use FMJ rounds not deliberately designed to expand or fragment. In that world, if you slow the 55gr nato round, you end up with less devastating wound channels. To increase terminal effects, you can restore velocity, increase weight, or increase diameter (caliber). Since fragmentation has to be a happy accident, you can't (in the open) plan for it. Civilian enthusiasts and police agencies can select 5.56 rounds which use projectiles designed to expand or better yet fragment at velocities much below the military threshold. This restores much of the 5.56's lethality. We have to be careful to separate the 2 arguements when discussing 5.56/223 terminal effects.
Just some food for thought. Of course, shot placement is king. This has been said before. Also, individual people vary. Some die from damn near nothing, others walk through walls. That being said.... I would not want to have to defend myself with a slow moving 5.56 nato round. However, I DO enter houses with non-military fragmenting/exapanding rounds from short barreled ARs without worry. Move that out 300 yards, however, and I am not so comfortable. If a round will only tumble and not fragment, I do feel better with 7.62 heading towards the bad guy.
For those who are interested, I work in an arena where even when there is a war on, we still help train PJs and other military spec ops medics how to deal with bullet wounds because our experience is pretty darn extensive. They have us on blast, but we hold our own with penetrating trauma. I am also a fully entry qual'd TacMed provider who employs what I talk about. I'm not overseas, but I have gathered nearly a decade of pretty directed experience on the subject.
Sean
