by B. B. Pelletier
Today, I’ll discuss big parallax wheels, including those that are custom-made for field target, reticles and the effects of temperature on a field target scope. Let’s start with parallax wheels.
You know that parallax adjustments are used for rangefinding. The shooter focuses on something close to the target or perhaps on the target itself. Then he reads the yardage to the target from the parallax wheel on his scope. So, my first piece of advice is this: Get a side-focus parallax scope! Back before they had sidewheel scopes, we all had to reach way out in front where the objective bell was to focus the scope. In the first place, that’s a long way to reach while holding an 8- to 14-lb. field target rifle with one hand. Second, many of those bells were hard to turn. On cold days they all were. All of us embraced the sidewheel scopes when they first came out in the mid-1990s. You only have to shoot half a match to understand why you want a sidewheel parallax-adjusting scope.
It was airgunners who gave the world sidewheels to begin with! Oh, side FOCUS parallax adjustment was first offered by Hakko, but it was a field target competitor who enlarged the small focus knob and turned it into a huge wheel. Why did he do that?
The evolution of the big wheel
It didn’t happen overnight. It took about three years for the huge sidewheels to come into vogue. But once they did, small knobs became things of the past. It was like the day after the Colt Peacemaker hit the market–nobody wanted a cap-and-ball revolver anymore.
Field target competitors do not use the numbers the factory engraves on the parallax adjustment wheel or objective bell. They learn real quick that those numbers are ballpark numbers only, not precise estimates of distance. For deer hunters, it doesn’t matter. A deer can’t tell when it’s hit an inch high or low, as long as the bullet is in the breadbasket. And a varmint hunter can miss his mark by a half-inch and never be the wiser. But a field target competitor has to hit within hundredths of an inch of where he aims at all times. So it matters to him whether the target is 44 yards or 47 yards away.
That huge sidewheel lets a competitor mark the smallest range differences on a piece of tape wound around the rim of the wheel. The larger the wheel, the easier it is to see differences in range after focusing the scope.
2007 National Field Target chamption and 2007 World Field Target champion Paul Cray has a huge sidewheel for parallax adjustment so he can read fine differences in the distance to the targets.
Before the side-adjust scopes came out, we put white tape around the objective bells of our scopes and calibrated them manually yard-by-yard on a range where the distances to the targets were measured. Duffers like me who were just out for fun, not blood, sometimes squeaked by with five-yard increments–at least in the middle ranges of 20-35 yards, where the trajectory was relatively flat. But to be perfectly honest, I was using a Bushnell Trophy 6-18x scope in those days, so I couldn’t really determine ranges past about 35 yards anyway. I marked out five-yard increments on the objective bell all the way out to the end of the course and had all my fun just looking at the pretty targets and talking to everyone.
However, those who adjusted the elevation for every shot–the clickers–had special elevation knobs made of Delrin. They were bigger, so they could fit a scale of yardages around the periphery of the knob, thereby being able to tell exactly how many clicks they needed for every shot and any range. Remember, field target takes place between 10 and 55 yards, and it was 50 yards in the old days when I first competed. So, there were a lot of lines on those big knobs, and they had to be made larger than standard so we could see the small lines and yard markings we had to put there.
This A-Team elevation knob is for Bausch & Lombe scopes. I had one similar to it. Put white tape around the knob and mark off the places where every range to the target is located. Use several different colors to indicate different temperature ranges! It’s taller than a conventional knob, too, and accommodates even more marks.
You learned a lot about ballistics while doing this. For example, you learned that for every close range marking on your scale there was also a long-distance yard marking at exactly the same point–the 23-yard mark may also have worked for 39 yards, and so on.
Back when I shot field target, the mil-dot reticle wasn’t common. The most favored reticle was the duplex. The holdeover crowd got five aimpoints out of it, and the click adjusters found it was easier to locate the thin central crosshairs in a dappled light situation. If you don’t know what a duplex reticle is, read this and this.
A plain reticle isn’t suitable for field target use. It will either be too thin to see in poor light or too thick for aiming precision on small kill-zones. Mil-dot reticles are fine for field target. They make the thin lines easy to see and give the holdover crowd plenty of auxiliary aimpoints.
There is no “best” reticle to use in this game. It all boils down to personal preference and your ability to see the reticle under various light conditions. It can take years to find a scope you like; and when you do, the specifications will probably mean less to you than intangibles like the reticle type, the exit pupil criticality and clarity in low light. For me, either the duplex or the mil-dot reticle seems to be the ticket.
The effects of temperature on a scope
You get all sighted-in, your scope is optically centered and you think you’re ready for the big dance. Then the temperature drops 20 degrees during the match and throws off all the careful work you did to calibrate the range scale. Yes, temperature has a dramatic effect on a scope, and field target will bring that out like no other sport I know.
The top shooters don’t have one range scale on their parallax adjustment, they have three–set up for gross temperature ranges! And they may have two or three different range scales set up on the vertical adjustment knob, as well. The course I used to run in Maryland hosted many of the top shooters in the nation, and I got a chance to see the incredible lengths to which they went to know the last foot to every target.
With all this anal work involved, it’s no wonder that I competed as a holdover shooter for the first two years I shot field target. However, one day I thought about how nice it would be to actually win something, so I bit the bullet and bought both a better PCP and a bigger scope and decided to adjust for each shot. Today’s report has actually been a brain dump about adjusting the scope for every shot. Next time, I’ll tell you what all us holdeover piggies were doing in the background while the prima donnas were winning our matches.