by Tom Gaylord, a.k.a. B.B. Pelletier
Today, I’ll use the new Air Arms TX200 Mark III to test how a red dot sight works on a precision air rifle. This test was requested more than a year ago by blog reader Mannish in Mumbai.
Going into the test, I thought about the recent test of how high and low scope magnifications affect accuracy on the same air rifle. That test was suggested by blog reader duskwight from Moscow; and not only did I test the premise (in Part 11), he also tested it with a special guest blog. Both of us discovered that the magnification has no bearing on accuracy, and duskwight’s test was skewed toward favoring the lower-powered magnification!
I’m shooting the new TX200 Mark III with a Tasco Pro Point 30 red dot sight. The sight does not magnify the target at all; so, in essence, I’m shooting with open sights. I chose 25 yards indoors for the test, feeling that was enough range to show the trend. From the past testing of this rifle, I selected the H&N Baracuda Match pellet because I thought that it had demonstrated the best grouping at 25 yards. It was only after the test was completed that I discovered I’d selected the results of the other TX200 that’s my personal rifle. Oh, well! I do make mistakes from time to time.
Baracudas are still very accurate pellets in a TX200, and today’s test was not invalidated by their use. When you see the results I got, you’ll agree that this test is valid.
Dot sights in general
A dot sight is one that projects a red light in the center of the lens on the inside of the sight. No light leaves the sight, so this is not the same as a laser. Only the shooter sees the dot.
The dot is adjusted to shoot the pellet to the place you want it to go. The adjustments are the same as for a scope, but there’s no erector tube involved. Think of the dot as the intersection of the crosshairs. Canting the rifle is still possible and has the same affect. And, on a quality sight like this one, the brightness of the dot can be varied. That’s important because, as the dot grows brighter, it also appears to grow larger — covering more of the target. You want to cover as little of the target as possible, while still being able to clearly see the dot in the light you have. The Tasco Pro Point has a rheostat with 11 different brightness settings.
I adjusted the setting to No. 8, which gave me a dot I could see, yet was smaller than the black bull on the 10-meter pistol target I was using. I found that using the dot was the reverse of using a precision target aperture sight with an aperture front insert. There, you encircle the bull with the front aperture — with the dot you place the red dot inside the black bull, so the black encircles the red. Once I figured this out, I was satisfied that I could aim with precision.
The first shot was fired from 12 feet and landed at 6 o’clock, just below the bull. I was on paper, so it was safe to move back to 25 yards, where I fired a second shot. This one landed at about the same height as the first, but 2 inches to the right. I adjusted the sight up and to the left (the adjustments work just like the ones on a scope) and shot again. The third shot landed more to the left but was too high. The sight was adjusted again and the next shot nicked the 10-ring of the bull, so sight-in was completed.
I fired 9 more shots with this sight setting and never once looked through the spotting scope. The rifle was rested on a sandbag because we’ve learned the TX200 does very well that way. With each shot, I paid particular attention to centering the red dot inside the black bull. That was easy to do because I had the dot sized perfectly against the bull. But on shot 7, I noticed that the sandbag had moved forward by several inches, so the rifle wasn’t always resting at the same spot. I would correct that when I shot the second group.
When the group was finished I walked down to the trap to change targets. The first time I saw the group was when I entered my garage and saw one ragged hole! Holy cow! I did it! The dot sight is incredibly accurate!
While this group looks very good, it’s almost double the size of the 0.336-inch group I shot from my own rifle at 25 yards with this same pellet while using a scope. So, it does appear that using no magnification has opened the group just a little. The next group would tell for sure.
Back I went to 25 yards to fire a second group. This time, I paid attention to the exact spot that the rifle was rested on the bag, and I was also careful to center the dot every time. I really thought this group would be smaller than the first. When I walked down to see it, however, it was not only clearly larger — at 1.177 inches between centers — but it was also very horizontal. The first group had been vertical, if anything. I wondered what had happened.
Ten H&N Baracuda Match pellets made this very horizontal 1.177-inch group at 25 yards. This is clearly not as good as the first group, plus what’s with that flier on the right? There were no pulled shots in this string!
The first group had satisfied me that the dot sight was accurate. Perhaps I was losing concentration by the second group, which really wasn’t that many shots. Only 24 shots in all had been fired. And why had the rifle thrown a shot wide to the right like that? It was almost as if the sight was loose or something.
That was when I remembered that I had done nothing about installing a vertical scope stop with this dot sight! I preach about scope mount slippage all the time to you readers, but apparently I can’t be bothered to do it right myself.
Sure enough, an examination of the mounts revealed they had slipped backwards on the rifle by 2 full inches! The Tasco mounts are 11mm; but being made for firearms, they have no provisions for a vertical scope stop, and so the inevitable had occurred. Naturally, I didn’t discover this until the range was completely knocked down and put away.
All that work for nothing because I didn’t use a scope stop. The rear mount is only on the rifle by about a quarter inch! No amount of clamping pressure, alone, can hold a scope mount or this dot sight mount from moving, unless you’re using BKL mounts.
I don’t think this is so bad. After all, the rifle and sight turned in a good performance, even when the mount was not locked down. Imagine what it might do if it was solid.
What do I do?
There’s only one thing to do — rerun this test. I will install a vertical scope stop next time, and I’ll show you how easy that is to do. Then, I’ll shoot the same pellets at the same distance, and we’ll see exactly what a red dot sight can do. Since this was supposed to be the final test of the new TX200 Mark III, it seems I have a reprieve. I can’t argue with that!