Book Chapter 9-Home

Hunting Bullet Metrics

Apply Terminal Performance Truth

AFRICA HUNTER QUEST©

Chapter 9 - DEFINING THE AFRICA HUNTING PROBLEM

GG was hard at it, or in the words of Sheriff Buford T. Justice, “in hot pursuit”. The impact patterns on his targets 200 yards away had figuratively lit up like a neon sign, pointing to the path of the load for the 30-caliber 200-grainer he had selected for short range hunting using his 300 Winchester.

The bullet had been vetted by both Fackler box testing into dry newspaper and 20% synthetic ballistic gel, both tests at 135 yards. In GG’s intended hunting application, ‘short range’ meant shots less than 250 yards.

The 200-grainer was a bonded-lead core bullet. GG wanted to keep the impact velocity on game between 2400 and 2800 fps. Although the manufacturer’s recommended impact velocity range was from 2000 to 2900 fps, GG wanted 2400 fps as a lower bound. Nathan Foster had indicated this velocity was a threshold for 30-caliber bonded-lead core bullets, above which “emphatic” terminal performance could be expected. GG’s ballistic software indicated an impact velocity of about 2400 fps occurred at 250 yards, assuming that the muzzle velocity for the load he was tinkering with didn’t appreciably change. Based on the group patterns he just shot at 200 yards, it didn’t appear that it would. Not only that, it was apparent that his three-shot group objective of less than ¾ inch was only about 1 to 2 thousandths of a seating depth adjustment away.

GG had already finished his ‘long-range’ 300 Winchester load using a 240- grain match bullet onto which he had manually installed a polycarbonate tip. In this case, ‘long range’ was from 250 to 600 yards. These yardages were predicated on the accuracy he had gotten during load development, the muzzle velocity of the final load, and the impact velocities he had achieved on game in Africa using a poly-tipped, 350-grain .375-caliber match bullet. As with the 240-grainer, he had manually installed poly tips on the 350s to get these match bullets to positively expand upon impact instead of potentially penciling through the animal. He had used the 350s to take springbok at ranges of 181 to 364 yards. Back-calculated impact velocities were about 2260 and 2100 fps, respectively.

The terminal performance of the 350s had been spectacular, with all animals dropping to the shot. All bullets completely passed through the animals, including a

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front quartering shot. Diameters of the exit wounds of the full broadside shots were judged to be from bigger than a 50-cent piece to slightly larger than a silver dollar.

Since both the 240 and 350-grainers were from the same manufacturer, GG had assumed that the jacket metallurgy, jacket thickness, and lead metallurgy would be comparable, if not the same. As such, he expected the general terminal performance from the 240-grainer would be comparable to that from the 350-grainer, provided similar impact velocities were achieved.

GG had made a premeditated attempt to slow both the 200 and 240-grain loads by shortening the barrel from 24 to 22 inches. He wanted a muzzle velocity of less than 2900 fps for the 200-grainer to keep the bullet within the manufacturer’s upper recommended impact velocity range. However, he hadn’t lost as much velocity as he had expected. His gunsmith had throated the otherwise SAAMI spec chamber to accommodate the uber-long 240-grainer. The longer throat had also allowed more powder to be used in the 200-grainer’s load before reaching maximum pressure. He had been expecting around 2800 fps for the 200-grainer, but was getting about 2860 fps, damn-near perfect.

The muzzle velocity of the 240-grainer load had also surprised him. His targeted muzzle velocity had been 2500 fps. That muzzle velocity would give an impact velocity of about 2250 fps at 250 yards, the same impact velocity of the 350-grainer at that distance. However, the final load had produced a muzzle velocity of 2640 fps. That muzzle velocity resulted in an impact velocity around 2360 fps at 250 yds, a good 160 fps more than the 350-grainer at the same distance. That was not necessarily a good thing, as the wound cavity volume and penetration length could have been adversely affected. But his gel testing on the 240-grainer at 135 yards indicated its performance would likely pass muster at that 250-yard distance.

GG had wanted a relatively short barrel for another reason: maneuverability in the thick brush. One year he had taken his 358 Winchester with a 21-inch barrel. The difference between it and the 24-inch barrel on his 375 H&H was amazing. Noise during the stalk was considerably less because the frequency of branches making a grab for his barrel was reduced. The shorter barrel was now at head level instead of above it when he carried the rifle on a sling. Ducking just his head was now sufficient instead of trying to (badly) estimate how much further he had to duck to avoid thrashing his barrel through the branches.

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GG was focused on seating bullets when he sensed the Pilgrim’s presence. He looked up, and there was the Pilgrim walking toward him, a look of apprehension on his face. “He doesn’t want a called strike three,” thought GG.

D: Good morning, sir. I bought Robertson’s book and have read the first five chapters. There are things I understand, but there are some I don’t. I’ve also thought about what you said about defining my problem. I’m not sure I can do that to the extent it needs to be done, and would like your help.

“Finally,” thought GG. “Base line, common denominator concepts and vocabulary. Maybe we are finally out of the ditch.”

GG: Fine. Pull up a stool and sit a spell.

Your hunting problem definition has two levels. The first level is very broad and considers factors and issues applicable for most any hunt. When you work through this first-level definition, you may find issues of concern that may cause hunting plan limitations, such as taking no shots beyond a certain yardage. This first-level analysis presents hunting plan strategies that will need confirmation, based on what your second-level analysis reveals.

The second-level hunting problem definition focuses on the terminal performance of the selected bullet and chambering. This analysis is based on my empiricism. This analysis could indicate a different bullet weight or generic design may be required to comfortably conform to the requirements identified in the first level.

D: That is so abstract.

GG: I know. It’s a fancy way of saying that what you want to use might not be such a good idea based on the animal and the conditions under which it will be hunted. The entire definition process identifies where and how you are vulnerable and indicates where you might find some relief if you feel you can’t change a bullet or chambering. Regardless, you can decide what options for relief appear reasonable, then choose the ones that you can live with.

D: So, the first level is a broad cut that may indicate what I have selected would work?

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GG: Sorta. There should always be a second-level analysis to check that the actual bullet you want to use in the intended chambering is up to the task. That task is mostly laid out in the first-level definition. The second-level analysis using the empiricism is where it becomes obvious if the bullet and chambering combination you want to use will work comfortably or is marginal. If it’s marginal, you potentially have hard choices to make.

D: But the entire definition process will allow me to see all the issues so I can make an informed choice?

GG: As far as I’m concerned, yes. For now, I want to only talk about the first-level definition factors. For the second level I need to introduce more concepts about bullet performance and generic bullet designs for you to feel like you can make reasonably informed decisions. You got an introduction to those topics when I talked about the conceptual wound cavity model.

I suspect you have read more than the first five chapters in Robertson’s book. What problem definition factors have you identified?

D: I don’t know the likely shot distances.

GG: Good for you. You have picked out the factor with the most interrelationships with the other factors and issues. But I would like to begin by first asking, what hunting method do you want to use when you are in Africa?

D: Either spot and stalk or walk and stalk.

GG: Bravo. In my mind, these are the best ways to appreciate and savor the Africa hunting experience. If those are the preferred hunting methods, what can you conclude about potential shot distances?

D: Unpredictable, highly variable. Could be 50 or 500 yards.

GG: Spot-on. Hunting from a blind would narrow the range of shot distances, and likely limit them to way less than 500 yards. Limiting shot distances or precisely knowing what the shot distances will be can make the entire definition process way easier. Making the effort to ask your outfitter what distances he expects is pretty much a ‘must’ to develop an applicable plan. What are some other reasons why knowing shot distances is important?

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D: Once I know the shot distances, I can determine the bullet impact velocities.

GG: Excellent. Why would you want to know impact velocities?

D: So I could estimate or have a reasonable expectation of game weight based on either Matunas’ or your empiricism.

GG: Yep. When you do that, you are dropping down to the second level with an assessment of the bullet’s terminal performance. This assessment is based on the bullet’s weight, impact velocity, as well as the bullet’s generic design. Any other reasons why shot distance is important?

D: I don’t know.

GG: How about scope zero?

D: I don’t see the direct connect.

GG: The scope zero you select should be a strategic compromise to accommodate what you believe will be both a minimum and maximum shot distance. You don’t want your bullet to impact too high at your short-range distance, nor too low at your long-range distance. Ideally, it should result in a universal point- and-shoot application. For most modern chamberings with muzzle velocities greater than 2800 fps, that zero will be about 200 yards for a typical Africa application.

Would there be any circumstances where at least two different scope zeroes could be required?

Donny was momentarily stumped, but then began to ‘think out loud’.

D: Two different scope zeroes would mean two radically different shot distances. If this were for the same animal, that would imply that terrain, vegetation or both were significantly different. If the vegetation was the same, that could mean the terrain became different, changing say from flat to hill and gully. If the terrain was the same, that could mean that the vegetation was different, say changing from grass or knee-high scrub to thick, head-high brush.

GG: Absolutely. Vegetation and terrain are important for other reasons as well. Both have implications on the second-level evolution of terminal performance.

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Terrain could indicate that the desired terminal performance would be to literally stop the animal. An example of this would be sheep hunting where you wouldn’t want the animal to run 25 yards, then fall off a cliff into never-never land. The vegetation or terrain could be so adverse that you might want mandatory full penetration of the bullet for an enhanced blood trail for tracking.

Does the shot distance also suggest that there needs to be a critical evaluation of accuracy?

D: Yes. For a shot at 50 yards, just about any accuracy would work. For a shot at 500 yards, the accuracy of the rifle and ammo system would become very important. Not only that, my shooting position must be different. I could take an off-hand shot at 50 yards, but would need to be prone for the 500-yard shot.

GG: Accuracy affects your assessment of an allowable shot distance. You just introduced a new first-level definition factor: shooting position. Shooting position affects accuracy, and in turn, affects shot distance. What other interrelated first-level factor would you need to consider under the accuracy banner?

Donny felt overwhelmed. This line of questioning had morphed into something that was abstract and surreal. “Not all of this is important,” thought Donny. “It couldn’t be.”

GG saw the Pilgrim shut down and bow up. He had seen it hundreds of times. He could almost hear “Not all of this is important,” maybe transitioning into “He just wants to hear himself talk,” finally into “He just thinks he’s smarter and better than me.” It was time for a preemptive strike.

GG: For starters, how about the actual size of the target?

Each shooting position with attendant method of rifle support has an accuracy expectation that can be expressed in terms of MOA. For example, if you shot just a laser off of sticks, a laser beam dispersion could be 2 to 3 MOA simply because of the wobble associated with that shooting position. If you shot seated off a bipod, that dispersion would be about 1 MOA. Prone, from about 0 to ¼ MOA. The dispersion from the shooting position has to be added to the group dispersion from your load, which is always more than the MOA that is implied by the group size at 100 yards.

If your target is the heart because you want to enhance the odds of stopping an animal, that target is about ½ the size of the lungs. For Africa plains game, you

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can conservatively figure that the average heart diameter is on the order of five inches, and that an equivalent average lung diameter is on the order of about 10 inches. For any shooting position selected, that means the distance for an effective heart shot is about half the distance for a lung shot.

Vegetation and terrain affect shooting position, and thus could potentially limit shot distance due to accuracy considerations. For example, you typically can’t shoot from a prone position in the bush. The height of the grass will determine if you need to shoot seated off a bipod instead of prone. The grass height could be so tall that you may have to shoot off of sticks. You might be able to shoot prone off a ridge top down into a thickly vegetated valley. All of these factors wind up being incestuous bastards, and their resultant interaction could ultimately affect the shot distance you allow yourself to take.

All of the above imply that the hunter has the skill set to make the shot. Is that assumption valid?

D: Only if the hunter has actually practiced shooting from the various positions.

GG: Yep. Now, literally visualize yourself in a prone position with ammo and a rifle suitable for a slam-dunk lung shot on a kudu at a lasered 300 yards. What wild-card factor could be in place that could be responsible for an unrecovered animal?

D: Wind.

GG: Yep. Is wind a first-level definition factor?

D: Yes.

GG: Have you noticed that there is an unspoken assumption concerning the hypothetical shot you have just visualized?

D: Shot angle?

GG: Bingo. What have you been assuming?

D: Broadside.

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GG: What if the only shot that presented itself was a rear quartering shot? Would that change your assessment of your 300-yard shot on the kudu from the prone?

D: It would. The shot would be more risky. The actual aim point on the animal would be less precise because of the shot angle. Plus, the shot may have to travel through the rumen to get to the boiler room.

GG: Outstanding. Can we officially now add shot angle to one of our first level definition factors?

D: Yes.

GG: For a rear quartering shot on a kudu off of sticks at 300 yds, how about the hunter’s decision-making skills?

D: Such a shot would likely result in kissing the trophy fee good-bye. No shot is way better than a bad shot.

GG: What if the animal at 300 yards was a lion instead of a kudu?

D: Taking the shot would be a really bad idea.

GG: This is going to sound like a trite question, but I want to draw something into sharp focus. Why is our hypothetical shot at a lion at 300 yards a really bad idea?

D: Because a lion is dangerous.

GG: Would you call it dangerous before the shot or after it?

D: Both.

GG: Dangerous in that it could kill you no matter what the hunting circumstances?

D: Yes.

GG: You said you wanted to hunt a gemsbok and a black wildebeest. Are these animals dangerous?

D: No. They are plains game.

GG: Same question that I asked you for the lion: dangerous before or after the shot?

Donny frowned. He sensed he had been ambushed and recovered the best way he knew how.

D: I don’t know. Are you saying these animals can be dangerous if wounded?

GG: Yes. These and several other species of plains game have downright nasty dispositions when wounded. A trophy bush buck weighs about 140 pounds, about the same weight as a good southern whitetail buck. Wounded bush bucks account for more hunter deaths each year in South Africa than all other species combined

D: What?!

GG: Found that out from my PH the first time I went over there to hunt. If wounded, they hide in thickets and ambush you, essentially taking out your privates. Hunters bleed out very quickly before they can get to help.

Has talking about the animals and whether or not they are dangerous suggested the last first-level hunting definition factor?

D: Risk?

GG: Bingo. Risk to life and limb. Any other category of risk?

Donny’s response was automatic.

D: Financial. You talked about it in conjunction with the kudu. If I were to wound an animal and not recover it, I would be out the trophy fee.

GG nodded his head. The Pilgrim was a sharpie when he wanted to be. He had begun to connect the dots.

GG: Outstanding, Pilgrim. You have just identified what I believe are the most significant first-level factors in defining any hunting problem, particularly in Africa. How about you give me a summary laundry list with any points of significance you think are relevant.

Donny thought for a minute to assemble his thoughts. He recollected at least a dozen factors, most all heavily interrelated. GG had forced him to focus on those interrelationships, and the factors now made reasonable sense.

D: The starting point is hunting method. That introduces both the first and second-level definition factors of shot distance. Shot distance affects scope zero. Allowable shot distance is influenced by vegetation, terrain, accuracy of the system, shooting position, target size, shooter’s skill, and wind conditions. Other first-level definition factors are shot angle, animal risk, and financial risk. Second-level definition factors assess the bullet and its ability to produce desired terminal performance, and are all related to impact velocity, bullet weight, and generic bullet design.

GG: Outstanding! You are officially on the path.

Donny knew it as well. Disparate concepts and assessments had begun to knit themselves together in his hunting problem mosaic.

D: Do you have a piece of paper and a pen? I need to write these factors down.

GG handed Donny an 8½ by 11 sheet of paper with his 200-yard aim boxes copied on one side. Donny turned it over and began to write:

- Hunting method

- Shot distance

- Impact velocity

- Scope zero

- Vegetation

- Terrain

- System accuracy

- Shooting position

- Aim point target size

- Hunter skills

- Wind

- Animal and animal risks

- Financial risks

D: You have repeatedly said that second-level terminal performance is related to the bullet’s impact velocity, weight, and generic design. I get the weight part. Although I don’t know precisely why, I understand the bullet’s design could be important. I have no idea how a bullet’s impact velocity controls its terminal performance. Is there a simple explanation?

GG: Ya got 5 minutes?