Penetration Index

The pentration Index was introduced in the year 1996 by A. Alphin in his book Any Shot You Want. The penetratin index describes the penetration of different kind of bullets. This index is useful for big game hunters when planning a hunting trip to Africa. Find out what else you have to consider when going big game hunting in Africa.

siehe: Alphin, A. (1996): Any Shot You Want: The A-Square Handloading and Rifle Manual.

How to calculate the penetration index

To calculate the penetration index you have do devide the kinetic energy of the bullet with its frontal head. Afterwards you multiply the result with the sectional density. The sectional density is a ration of the bullets mass to its cross sectional area square.

The penetration index when hunting elephants

The penetration index shows how suitable bullets are for big game hunting. The higher the index the better bullets fit.

• A bullet with a penetration index lower than 85 isn’t suitable for hunting elephants.
• A shot to the head of a big game, with a penetration index from 85 to 100 works but isn’t recommended.
• Bullets with an index from 100 to 130 are suitable for hunting elephants.
• Any index above 130 is perfect for a shot to the head of an elephant.

Although a penetration index of 130 does not mean that it has double the penetration of a bullet with an index of 65. All the figures are relative. Depending on many difference influencing factors within the target a perfect theoretical calculation is impossible.

Get all the latest information about hunting elephants in Africa.

Field observations

Field observation have schown some interessting facts during a hunt with a penetration index of 132:

• A side shot to the brain of the elephant has exited the head on the other side. The shot had a 45° degree and a penetration of about 40”.
• A frontal shot between the eyes of the big game has damaged both brain and rips. The penetration was 80”.
• A brain missing side shot to the head of the elephant had a penetration of abou 30”. The projectile hitted the very hard atlas joint and didn’t go any further.

These observations show, that the penetration index is a theoretical indicator for big game hunters. Factors like the angle of the shot or the different parts of the big games body influence the pentration of the projetiles.