Sniper school is one of the very few courses a SEAL will not be looked down upon for failing to complete. It’s an unwritten rule that you don’t give guys a hard time for washing out of sniper school. Because the course is known for its insane difficulty, just being selected or volunteering to go automatically elicits respect in the teams.
Here Webb describes the mental side of long-range shooting and how you can think about it:
Some of our most extensive classroom study was in the area of ballistics, including internal ballistics, externals ballistics, and terminal ballistics.
Internal ballistics refers to what’s happening on the inside of the rifle. When your firing pin hits the bullet’s strike plate, it sets off an initial powder charge, and the exploding powder creates a rapidly expanding gas bubble, which propels the slug, or front portion of the bullet, through the chamber. It’s very much a miniature version of a rocket ship launch: just as the rocket discards its boosters once it’s in flight, the rifle ejects the empty cartridge, sending only the relatively small front portion on its journey. In the rocket’s case, that’s the capsule that houses the astronauts. In the bullet’s case, it’s the death-dealing slug.
The inside of the rifle’s barrel is inscribed with a series of spiral grooves, or rifling (where the term rifle comes from). This puts a fast spin on the bullet, giving it stability in flight, much the way you put a spin on a football when you throw it. Internal ballistics has to do with how many twists there are in the barrel and their precise effect on the bullet, how fast the bullet travels, and how it’s moving when it exits the rifle.
This is where external ballistics takes over. Your bullet will start its journey at a velocity of over two thousand feet per second. However, the moment it emerges from the barrel its flight path is already being influenced by its environment. Leaving aside for the moment the effect of wind, there is a universal drag created by the friction of that ocean of air the bullet pierces through in order to fly, combined with the downward pull of gravity. At a certain distance, different for different weapons and ammunition, your particular rifle bullet slows to the point where it passes from supersonic to subsonic. As it eats through the yards at rates of something like one yard every one-thousandth of a second, the integrity of its flight path starts becoming compromised. A .308 bullet traveling at 2,200 feet per second will lose its flight-path stability to the point where it starts tumbling head over heels by about 900 or 1,000 meters out.
External ballistics is also about exactly what that flight path looks like. When you shoot a .308 at a target 800 yards away, you’re not shooting in a straight line: it actually makes a pretty big arc. Imagine throwing a football from the fifty-yard line to the end zone. You don’t throw it straight toward the goal; instead, you know you have to throw it upward so that it arcs through the air, hitting its high point at about the twenty-five-yard line and then curving back down to reach the end zone. The same thing happens with the .308 bullet: you’re not shooting it in a straight line, you’re really throwing it up in the air so that it arcs and comes down where you want it to. Understanding exactly how that works can have a make-or-break bearing on your successfully hitting your target.
For example, let’s say you’re shooting at something 800 yards away. In the terrain lying between you and your target, you notice a low-hanging bridge. From all appearances, that’s no problem. Your target stands at maybe five foot eight; you are lying on the ground, on your stomach; and the bridge is a good ten feet off the ground at its lowest point. When you sight down through your scope at the target, you can see a clear pathway from you straight to the target. No problem, right?
Wrong. That bridge may not look like it’s in the way—but when you take into account the arc your bullet needs to travel to land at your projected site, that bridge could be lying directly in the path of what we call the bullet’s top arc.In other words, it could stop your bullet cold, halfway to your target. And in the kinds of circumstances a sniper will often be facing, you may not have the luxury of a second shot. You have to know your bullet’s maximum ordinate, that is, the maximum height that bullet will travel on its path to your target, and calculate for that.
Once we had mastered the M14 we moved on to other weapons, starting with the .308 bolt action Remington, a very solid weapon and quite capable out to eight or nine hundred yards, in the right hands. This was our first look at a real scoped weapon—and right away, I knew had a problem. There was a Leupold scope on one of my guns that just didn’t seem quite right. I pretty quickly realized that it wasn’t maintaining at zero: it was slipping off. There was no way I could shoot with a scope that wasn’t reliable.
