Home Forums Hunting & Shooting Africa penetration/velocity correlation

On African game like rhino,hippo,buffalo,etc, is there a point at which a bullets velocity being higher ceases to result in increased penetration? For example, the .416 Rigby is one of the best known penetrators2400fps,and the .458 Lott resulted in a great increase in penetration over the .458 Win, but if they had built the Lott round to go 2800fps instead of 2400fps,would it have penetrated even more,or is 2400fps the "magic number"for African cartridges performance and penetration?

If i had two Barnes .458/500 grain solids, and fired one at 2400fps and the other at 3000fps into the same medium,say an elephant or two, which would penetrate deeper?

According to Kevin Robertson in his book "The Perfect Shot" he states that above 2300-2400fps, bullets start to exhibit much more erratic penetration and terminal performance. For these reasons, he cautions against using super high velocity bullets, especially on dangerous game, unless taking very long range shots.

While I do not have nearly the experience with terminal performance on dangerous game as he does, my few experiences do line up with his.

To answer your question, I would say that the higher velocity bullet would have either the same amount of penetration, or less than the lower velocity bullet. It's tough to really say though because I've never actually tested this theory. 3000fps is extremely fast for that heavy of a bullet and a tremendous amount of stress is placed on it when it strikes a medium. At a higher velocity like that it is more likely that the bullet will deform, which will decrease penetration as well as make the bullet behave in an erratic and hard to predict manner.

There are literally thousands of posts on the AR forum, mostly focusing on solids around this very question. Art Alphin & co-authors discuss this in detail in their book "Any Shot You Want" as well. If you're talking about expanding bullets, bullet construction, velocity, sectional density and twist rate, plus the toughness of the animal (hide, muscle, bone, etc) in that order are probably the dominant factors. If you drive an expanding bullet past it's impact velocity range it will either come apart or expand so much that it's frontal area will decrease it's penetration. At the extreme it will not penetrate the vitals and leave you with a wounded animal.

The big bore Woodleigh soft points are great bullets but typically are designed for impact velocities of less than 2400 fps. TSX's love velocity, A-Frames are somewhere in between.

The dreaded answer "it depends" comes to mind

My Lott hand loads fire @ 2 096 fps. At 2 800 fps I would be wondering where the most dangerous side of the rifle is

"It depends" will sure feature.

At 2300 fps my 500 Jeffery is fun and easy to shoot, at 2400 fps I have to set myself and think about how I'm holding it, at 2500 fps it's just friggin painful. I keep my loads down to 2300

This is an interesting subject, I have no idea what the right answer is. As I read the above notes, I kept asking myself,,
What would Roy say?

My 458 Lott was built with a stock that was copied from an Over and under shotgun. It was a pecular looking arrangement but handeed recoild better then anything I have ever shot. It looked a bit like somebody blended a double rifle and a bolt action together.

Even so, my 2150fps loads with the Barnes TSX exited broadside on every buffalo hit, several were recovered in two different white rhino's shot, and several were recovered in body shot giraffe. Oddly enough I shot an escaping Gemsbok going straight away about 4" from the tail. That bullet was recovered in the neck.

When I loaded it to 2350 fps which was the maximum for me, the petals always broke off and the penetration was not noticeably better. The recoil was probably 50% more then 2150fps. It would rock you back and stun you with the shock of impact.

At 2150, which was my go to load, it was comfortable, as much as this power can be anyway. My Barrel was 22" and the gun with magazine full was 9.5 lbs.

Interesting.thanks for the replies. I was seeing those new "hydrostatically stabilized" Woodleighs are supposed to penetrate great on African game. Saw an article where a guy shot an elephant with a .458 Lott in the rear leg and it killed it with a brain shot using those hydrostatically stabilized bullets.

In one of P.O. Ackley's handbooks there's an article on testing wound's at Edgewood Arsenal, lot of years ago. One of the things that was mentioned in the article is that at some velocity, penetration lessen's even though velocity is increased.

thanks.i think that velocity is around 2400 fps in hunting context. i think the "it depends.." comes into play to.

it depends!!

The answer to this was discovered by Mr Roy Weatherby himself back in the late 40's. His cartridges pushed bullets of the day so fast that they would blow up on impact or shortly thereafter, limiting penetration extensively.

Today we have much better bullets that handle these high velocities, but penetration is reduced as velocities get higher, the reason is due to the 'parachute effect', which is the bullet expanding to a larger frontal area than what is ideal and slowing quicker because it has to displace more tissue.

Anyone who has used a bonded bullet will notice that the jacket stays closer to the shank than non bonded bullets, this is because the lead core 'hangs on' longer allowing the jacket to peel slower, reducing the peeled sections diameter as it is forced against the shank of the bullet. This action causes deeper penetration, but still disrupts plenty of tissue.

Hope this explains the fundamentals adequately.

Cheers.

True in concept, but there are variations in bullet design that prevent generalizations. Woodleigh Weldcores, for example, have very heavy jackets and some of their expansion diameters can be double the shank diameter.

Bullet construction is everything in bullet design an many principles of the past are no longer valid starting with SD as it is commonly and incorrectly used when experts are citing superiority in expanding bullets, where SD was never intended to be used.

Homogenous bullets have been the real innovation in our industry over the last 25 years. Although the basic concept is not new, the technology has been perfected so that tiny caliber and light bullet weights have achieved penetration levels unheard of before in their bullet class, the 130gn .308 caliber TTSX would be a great example, whereby it has recorded penetration on medium African plains game previously dominated by heavy weight, premium design bullet territory.

Never forget that the only reason bullet weight range per caliber exists, is because traditionally, using cup and core technology, the bullets fell apart so a percentage of retained weight and momentum could only be assured with an expansion restriction built into the design. Sometimes this was achieved by matching the bullet design to a velocity range.

What Roy Weatherby achieved, was push that velocity range more towards teh capability of the powder burning rates by designing cases larger enough to accommodate powder to bore ratio challenges.
The net effect was bullet were also challenged and many failed to the point that it created a new market for premium bullets able to withstand the stresses of increased impact velocities and still hold together to achieve the penetration levels we see today.

We owe Roy E. Weatherby a lot more that than just a "High Priest of Velocity" banner. He, in our time, generated the need for the bullet industry we have today.

John

+1! With today's bonded and monometals, the 460 Weatherby is the penetration king when it comes to 45 caliber DG rifles. Weatherby was ahead of his time and it took bullet technology fifty years to catch up.

Yes, but, non-expanding solids will react diffently to increasing velocity than a soft tip expanding bullet.