Systems analysis and the sighting-in of firearms

Monday, October 06, 2008 Filed in: Rifles, General gun stuff, Hunting

This weekend was the opening of general deer season here in Oregon. I could tell it was opening weekend, because our normally deserted gravel road, which leads into the mountains, has been turned into Interstate 5 for deer hunters! The parade of all the hopeful woodsmen (and perhaps not a few woodswomen) going after Bambi made me realize I'd missed something this year: hunter's sight-in at our gun club.

You see, last January my wife and I bought a new place. When we moved we gave up our club memberships, as a) the club is now 60 miles away, and b) we can shoot all we want on our own property. I don't miss the club, but I do miss the circus-like atmosphere of sight-in days. I actually enjoyed helping out those whose shooting skills were not, shall we say, fully developed. They needed all the help they could get!

(Sight-in days at our former club is a big event. It occupies every full weekend for a solid month; it's not unusual to have several hundred guns per day go through the system, as the club is one of the few rifle ranges within easy driving distance of the Portland, OR metro area. Working at sight-in means long days and lots of activity.)

In recent years I worked sight-in alongside my friends Georges and Maurice, who got the same kick out of the event that I did. We kept a running tally of the best, worst, and most over-gunned shooters on the line. During the lulls we'd trade stories of the unusual incidents we'd had, and not all of them were with customers!

One particularly busy day I had a run-in with one of the folks who served as Assistant Chief Range Officer for the event. I was helping a middle-aged fellow who'd arrived toting a .30-06 of unremarkable (though completely serviceable) pedigree. He showed me his gun, his ammo, and sat down at the bench. The club provided sandbags and front rests for the guns, but this fellow didn't want to use them. "My zero is different if I shoot from a bench than from my hands, so I'd just like to rest my elbows on the table." That was fine with me; this fellow had obviously been around the block more than once and thus knew what he was doing. (His target would later prove my analysis to be correct.)

He had just fired his second round when the aforementioned RO came rushing up. "He needs to use the rest", he sputtered. "He'll never know if he's properly zeroed shooting from his hands!" I told him that the customer knew his own needs, and that I admired the fellow for obviously knowing more than the average schmuck who came through the door.

This annoyed the RO to no end; he wanted to argue with me, insisting that I was a complete fool for letting the customer do this. I simply smiled, waved him away, and went back to my job.

The RO in question, like many, was confused about the reason we sight in a firearm. The goal of sight-in is to get all parts of the weapon system - the gun, ammo, sights, and shooter - in alignment so that the bullets land where desired. If we take away - isolate - any part of that system, we have removed a functioning part that will affect the outcome. The outcome is what we're testing! We're not testing the scope (which is what this RO was convinced we were doing), or the ammo, but the results that they - together with the shooter - produce. We have to test all parts of the system in concert, so that we can see if the goal is being met.

Let's say that we were to test the system using sandbags and a bench. There are very few rifles made that will have the same zero point no matter how the gun is suspended; the points at which the suspension occurs, the amount of pressure on the suspension points, the direction of that pressure, and even the resulting direction of recoil will all change when the gun is taken off the bench and shot from a field position. All of those will change the landing point of the bullet, sometimes dramatically.

Now consider the shooter's input. The head position from a bench is different than it is from standing (or even sitting or kneeling, and especially from prone.) The shooter's eye will not be in the same place relative to the sights or scope; the cheek weld point will be different; the shoulder will be further forward or backward, depending on the physique of the shooter. The shooting hand will shift position slightly, leading to a different grip pressure and direction of pull on the trigger. Think any of those might affect the outcome of the shot? You bet they will - all of 'em.

Change enough of those inputs, and you'll end up with a system that won't shoot to the same point of aim under the expected conditions. We need to check the system's alignment (gauged by the impact point of the bullet) under the conditions in which it will be used. For hunting, that means "not from a bench rest."

An extreme example of this can be found simply by looking at G. David Tubb's rifle. For those who don't know, he shoots with the rifle held at an angle, which is very different than what we were all taught to do! That doesn't matter, though, because he's set his sights to hit correctly with that unorthodox hold. Imagine we "isolated" his rifle; put it on a bench, cradled it level in sandbags, and proceeded to "zero" the gun. Guess what? It wouldn't hit the correct point, because it wouldn't be held in the position in which Tubb shoots the thing. Given his modest success at highpower competition (!), I'd say he knows what he's doing!

One day I was visiting one of the very best handgun trainers I know. I picked up her gun and was surprised to see her sights drifted quite a ways to the right. I thought that odd, but she pointed out that they were that way because that's where they had to be to allow her to hit where she wants the gun to hit. Given that she can regularly clean the clocks of just about any male shooter - some of them state and regional champions - at will, I'd say her system is working perfectly. That's all that matters!

Are there times when we want isolation? Certainly - when we're testing specific parts of the system. Comparing one load to another, for example, demands an isolated gun; we don't care exactly where the rounds hit, because we're interested in the differences between two inputs of the same type. In order to see those differences, we have to eliminate all other variables that might obscure them.

Sighting in, on the other hand, is all about the whole system. To align the system, we need all of its parts to be working as they normally do. The fellow on the line that day understood the concept; the RO didn't.

There is no substitute for thinking about what you're doing, and why you're doing it.

-=[ Grant ]=-

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