by Tom Gaylord, a.k.a. B.B. Pelletier

Part 1
Part 2
Part 3

TX 200 Mark III
BB’s TX200 Mark III.

Today’s lesson is about sighting-in a rifle scope. I know that scope mounting and sighting-in seems daunting, but it isn’t as hard as you might imagine. In the last report, I sighted-in at 10 feet. Because I got lucky, it took just 2 shots to sight-in the rifle; and when I finished, I told you I was ready to try the rifle at 25 yards. I said, based on the results of my 10-foot sight-in, it should be on paper at that distance (actually it would be on target at any distance between 20-35 yards, given the TX 200’s velocity), but it probably wouldn’t be exactly where I wanted it. Today, we’ll find out if that prediction is correct.

Let’s get to it
So, I set up the bench and started shooting at 25 yards. I chose H&N Baracuda Match pellets because they were the pellets I used at 10 feet. If you forget what happened during the 10-foot sight-in, you really should read that report first to appreciate what’s happened here. A quick summary would be that I guesstimated how high above the bore the center of the scope is, and shot at a dot the same distance above the desired point of impact. Aiming at the upper dot, I was trying to get the pellet as close as possible to the dot beneath, which meant the scope would be shooting to exactly the point of aim (offset by the scope and barrel centers) when all trajectory was removed from the equation.

TX 200 Mark III sight-in target shot 1
The two dots are separated by approximately the same distance as the center of the barrel and the center of the scope. Aim at the top dot and hit the bottom dot. This is the first shot. After I adjusted the scope, the second shot went through the bottom dot.

Shooting at 25 yards
The first shot at 25 yards landed slightly above and to the left of the bullseye. I then shot 4 more that moved over to the right just a little. I took the center of the larger 4-shot group as the place where the scope was really sighted, and I adjusted from there. In all it took me far less than 10 minutes to sight-in this scope, even though I spread the reports over a period of 2 weeks.

TX 200 Mark III 25-yard target first group
The first 5 shots at 25 yards landed high and to the left, with the very first shot landing farthest to the left. I took the center of the main group of 4 to be the point of impact. From there, I adjusted the scope down and to the right.

Bear in mind that I do not want to hit the dot at the exact center of the bullseye, if possible. That’s my aim point; and if I destroy it, I have to guess where to hold the crosshairs.

First group
Now that the rifle is sighted-in, I shot the first 10-shot group at 25 yards with the stock rested on my open palm, next to the triggerguard. I got a fairly good 9-shot group, but I managed to throw one shot to the left. Nine went into 0.376 inches, but that one stray shot opened the group to 0.605 inches. I was moving around too much in the artillery hold, and I could see it through the scope.

TX 200 Mark III 25-yard target second group
Nine shots in 0.376 inches isn’t bad for 25 yards, but a stray shot blew the group out to 0.605 inches.

Second group
Stability seemed to be my problem, so I slid my off hand out to where I could feel the cocking slot on my palm. The rifle seemed to rest steadier, but the group doesn’t reflect that. Ten pellets went into 0.714 inches, which is horrible for a TX200. Obviously, this wasn’t the right hold for the rifle. And just as obviously — I was having a bad day.

TX 200 Mark III 25-yard target third group
Ten shots in 0.714 inches at 25 yards is hardly something to be proud of for a TX200. It’s more of an outstanding group from a Chinese breakbarrel.

Sometimes, a disaster (okay, maybe just a small setback) contains the seeds of discovery! Since I couldn’t hold the rifle steady enough to shoot a good group on this day, could I rest it directly on the sandbag and do better? We’ve been interested in the fact that some spring guns don’t seem to need the artillery hold. I already told you the TX200 is one of them. Perhaps, this was the day to find out.

For the next group, I rested the rifle in the long vee-groove in the top of my sandbag. The bag is so long that the rifle rests there without needing a rear bag for support. It was dead-steady when I sighted this time.

The results tell the story! This time, all the shots went to the same place. The group is very round and tight, at 0.336 inches. This is clear proof that the TX200 can be bag-rested when shot, and also that the rifle is incredibly accurate. I’ve shot even better groups with it in the past; but whenever I do things right, I always get good groups with this rifle.

TX 200 Mark III 25-yard target fourth group
Shooting with the rifle rested directly on the sandbag produced the best group of the day. Ten shots went into 0.336 inches, and the group is relatively round, to boot.

Notice that in today’s test only a single type of pellet was used. That kept things simple and allowed me to look at other things without worrying about which pellet to choose.

So, we’ve learned 2 things. The first is that it’s easy to mount a scope on an air rifle and to sight it in. It doesn’t take a lot of time, nor do you need any fancy equipment. Of course, if your rifle has a drooping barrel problem there will be more to do, but these are the basics.

Second, we’ve learned that the TX200 can shoot as well or better when rested directly on a sandbag as it can with an artillery hold. That’s certainly true if you’re shaking when holding the gun.

Tomorrow is the 50-yard test, followed by a full test of a brand-new TX200 Mark III, I hope. There are some other things that can be explored with this rifle as our testbed. All in all, we have a lot of things left to do with this air rifle!