There is one aspect of hunting and shooting that is a “black-hole” for most sportsmen – terminal bullet performance. This is also called terminal ballistics. When hunting season approaches we take “old-Betsy” out to the range and shoot some holes in paper targets. The idea is to get the holes where we want them and as close together as possible. This is called sighting-in and it is about the only bullet testing most people do.
That is fine, we need properly zeroed rifles and also accurate rifles. BUT, this shooting does not tell us anything about what the bullets will do after they hit something – hopefully a big buck, boar or bull. Bottom line, if the bullet destroys vital systems (respiratory, circulatory or nervous) the critter expires quickly. If the bullet hits other systems, such as the digestive (also called a gut-shot) the animal will die but not quickly. This is why shot placement is so important – hit them correctly and they die fast. The optimum is what we call “BANG-FLOP!”, indicating that the nervous system has been overwhelmed.
Most hunters never encounter poor bullet performance but it happens. I have seen bullets explode on impact, failing to enter the chest cavity. I have also seen bullets penetrate without any disruption so that the majority of the energy was wasted on a rock behind the critter. The animals did not show any indication they had been hit.
Fortunately most bullets start to mushroom within a few inches of penetration and the mushrooming continues quickly. This imparts shock and bone busting energy to the critter and hopefully destroys vital organs. Deer are not very wide so we need bullets that initiate mushrooming and energy release within the initial four or five inches. Big critters take more penetration to get to theirvitals.
What constitutes poor bullet performance? Assuming that the bullet flies accurately the answers are failure to mushroom, failure to maintain a straight course after impact and the biggie – core/jacket separation.
Fortunately most animals die even if some of these bullet performance failures occur. Sometimes bullet failure is the reason for a lost trophy. Let’s face it, some bullets are very accurate but not great performers on game. This is particularly true if the impact velocity is high as happens with close shots. Some of the popular non-bonded plastic-tipped boat-tails have reputations for being “meat-grinders” when impact velocities are high.
There are also some “hard” bullets that do not disrupt at slower impact velocities or on smaller critters. The trick is to use these tough bullets where they are needed. I would gladly shoot Swift A-Frames, Winchester Failsafes and Trophy Bonded Bear Claws on moose or elk, but would go to a faster opening bullet for deer.
The farther a bullet travels the more velocity it loses. Another key variable is the cartridge. The .30-378 Weatherby shoots much faster than my .30-30 lever gun, yet they both shoot 150-grain bullets! Impact velocity is a key factor in terminal ballistics. So manufacturers must design bullets that upset or mushroom at a wide range of impact velocities. So how do we find out what a bullet might do at various ranges?
How does the average person compare what bullet X will do verses bullet Y? I have been testing some tests lately and will share some info. Water is the easiest. Simply fill a couple of garbage bags with water or better yet several plastic jugs. Then move back to the fifty or one hundred-yard mark and let fly. After the mist settles we can usually find the bullet inside a bag or jug. Just make sure that you have enough water to stop the bullet.