Velocity versus penetration

[MePlat]

Veral:  Do you go along with the belief of some nowadays that higher velocity will result in less penetration with a given alloy and bullet shape.
I am refering to the Randy Garrett beliefs on this as he does have a big following concerning this belief on the Marlin Site.
Could you go into some detail as to why this is so or not so?

Thanks.

[Lloyd Smale]

I know that from testing weve personaly done that theres very little differnce in penetration with the same bullet shot at 2000 fps out of a .50 alaskan then there is at 1300 in a .500 linebaugh.

[Veral]

In my experiance, when increasing velocity decreases penetration it is because the bullet expands more, breaks down, deforms, or perhaps yaws (unlikely with flatnosed that doesn't deform)    Always, when a flatnosed, nondeforming bullet is fired at higher velocity the wound diameter increases, which probably consumes much of the energy gained through higher speed.

Think of it this way.  When a fast bullets speed falls to something lower, it will penetrate the same distence from that point on as if it were to strike at the lower speed.

[Norm Watkins]

Oh boy! This is where I need to be careful. Veral, you have probably forgotten more than I will ever know about bullet performance.

However, the tests that Garret reported on seemed to demonstrate something unusual. A bullet launched at a certan range of slower speeds would actually outpenetrate  a bullet launched at a certain range of higher speeds. This does seem counter intuitive, because as you said, one would think that once the bullet slowed to that "sweet" speed, it would continue to penetrate from that point on as far as a bullet initially launched at that speed. Garret's test indicate otherwise.

The theory has been advanced that a fast bullet has "precompressed" the media so that the bullet slows down faster after it reaches that "sweet" range of speeds that normally would  allow greater penetration.  In other words, higher bullet speed has somewhat changed the nature of the medium being penetrated, making it more resistant, and slowing down the bullet at a higher rate than would be the case if the bullet had started out slower.

[Veral]

I think we are discussing nondeforming bullets, which means at handgun velocities primarily?
Number one.  If they are going too slow they won't wound large enough to kill quick.  So lets get them to kill speed first.  At that speed, the flatnoses I offer go through almost any game you'll encounter, chopping a good wound all the way.
For this reason, the concern about deep penetration isn't a concern.  If you have concerns about a specific bullet/caliber when ordering an LBT mold and I'll make a reccomendation, as you must understand my offerings are broad, so my answer here is general.
I haven't proven this by testing, but feel certain that the only reasons a faster bullet would penetrate less than a slower one is that the faster one either deforms or expands a little, which naturally makes it push more tissue and slow faster, or causes it to tip a bit, which hurts penetration depth.