Hunting in Tough Terrain, Part 2, Shooting Uphill and Down

The challenge of shooting uphill or down, aside from the difficulty of steep terrain itself, is not due to how different a bullet travels in such conditions, but that we generally sight our gun in on level ground.

The velocities of modern firearm bullets are such that for the distances of shots taken in typical hunting situations the bullet travels at essentially the same speed whether going flat, up, or down. And, in all these cases, gravity will cause the bullet to `drop' (straight down). One way to describe this drop is the fall from the line of sight. And this `drop' is also practically the same, whether shooting up, down, or flat. The big difference, however, in shooting up, or down, is that typically your gun is set up to accommodate for the drop while the bullet is traveling essentially flat (at the rifle range).

For example, on the rifle range (shooting approximately horizontal), a typical high power (big game caliber) bullet, traveling at, say, 2500 feet per second, will drop approximately 1 ft at a range of 200 yards. If we `sight our gun in' at 200 yards, however, we change the angle between the scope and the rifle barrel, so that when we `look' at the target, the barrel is actually pointed slightly upward. We pull the trigger and the bullet follows a shallow arc, going upward for a while above the line of sight (shooting high) and then comes back down to the line of sight (the cross hairs) as it reaches the target.

No big deal. We know all that.

Now let's shoot uphill (or down) at a 45 degree angle. (We hunt mule deer in such terrain - the mule deer love it - but it's quite a workout for us humans.) Two things are added to the `picture'. The bullet still takes essentially the same time to travel 200 yards (slope or path distance), and arrives on target with about the same speed. The bullet still `falls' 12 inches, straight down. Now it gets fun. The sight picture of 12 inches across the field of view now spans 17 inches of vertical drop. You pull the trigger, the bullet flies the distance to target and falls 12 inches, passing 5 inches high of the intended mark. Whoa. How did that happen? I just told you. This is for a bullet traveling an average speed of 2500 feet per second. At 300 yards the bullet passes 10 inches high. Whoa, you might very well have missed altogether.

The situation is further aggravated, and dramatically, if you don't accurately know the distance. Without knowledge of the actual distance it is likely you will over estimate the range, hold high, and end up shooting even higher. For example, if you estimate the target to be at 250 yards, and it is only 200, and you accommodate for the additional 50 yards by sighting (holding) 6 inches high, then at 200 yards your bullet flies 5 plus 6 or 11 inches over target. If your target is at 300 yards and you estimated it to be at 350, you will probably hold high on the order of 12 inches, and pass 12 plus 11 or 23 inches over target. Thus, you will often hear the hunter who comes back from his or her first hunt in steep terrain say, "The first shot went clean over the (animal) ... so on the next shot I aimed under it ... and got it."

Obviously the numbers will vary bullet to bullet, caliber to caliber, and so on.

So, what to do.

First, use a range-finder so that at least you know the actual distance to target. Second, for mild slopes, don't worry about it. For steep slopes, consider the following. Get an idea of the various slopes that you may be dealing with. Actual slopes of terrain may be calculated from topographic maps or output from topo map software. Our favorite mule deer hunting spot has a lot of terrain that is literally at 45 degree angles. For every one foot horizontal, the terrain climbs, or falls, one foot. It is very difficult walking. This is extremely steep terrain and most of the United States is much less steep than this. I don't know how the soil stays on the slopes. And if we are into cliffs, it is steeper. There are a few spots that are not as steep. But, or so, the worst case scenario is that we would be shooting straight down at 45 degrees.

Find a ballistics calculator. (Hint: type `ballistics calculator' in your computer search engine on the Internet and start exploring.) The calculator should have at a minimum the options of various bullet makes (or shapes and sizes), `zero distance', `line of sight' angle, and muzzle velocity. Input the various parameters of the bullet you will be shooting, and then look at the `drop' with various line of sight angles. Presumably you will be sighting in shooting horizontal, so to test the calculator (and to see if you know what you are doing), put in the zero distance, your bullet parameters, and the calculator should give you zero drop at your zero distance. The drops at other distances (shooting horizontal) should be comparable to the drops published by the manufacturer of your bullet. Now change the angle of sight and let the fun begin. Watch how the `drop' is actually high, and it is approximately equally high whether shooting uphill or down, for the same angle.

Think all these numbers through so that you have a good understanding of your bullet travel before you go into the field. At a minimum memorize the bullet drop for various distances out to the maximum distance you will take a shot, say, at 50 or 100 yard increments. Then, run some examples at some distances and angles you might encounter. For example, if my gun is sighted for zero at 200 on level ground, and I engage a target at 200 yards slope distance at 45 degrees down, I better actually aim about 5 inches low. If I engage an animal at 300 yards 45 degrees downhill, instead of holding 12 inches high (as I would on level ground), I should hold dead on. But if my gun was sighted for zero at 300 yards (on level ground), then I would hold twelve inches low.

The best remedy for all of this is to think it through in your mind (and on paper if need be) before the hunt. If possible, do some shooting in steep terrain to verify your thinking. One point of good news in all of this is that, even if it is steep where I am standing, and where my target is standing, if my target is `across' the canyon and essentially level with me, the bullet travel will be relatively level, and all I need to know is the distance, and shoot as I would at the rifle range.

The other bit of good news is that if the terrain is indeed as steep as I have described, there probably won't be many hunters where you are at, and if you have to shoot straight down hill, and if your first shot is a miss, whatever it is your are shooting at will probably look up at you in amazement and wonder how you got there, and maybe give you a second chance.