by B.B. Pelletier

I will return to the RWS Diana 34 Panther for one more longer-range test and a look at the velocity numbers, but it won’t be for several weeks. Torrential rains have swamped my regular rifle range and I have to find other things to do.

This comment came in yesterday from an anonymous reader. “Perhaps you can make a few suggestions for me. I seem to have all pellet guns shoot to the left and low. [They are] still on the target paper but not in any circle [bullseye?] and there are 10, an inch apart and the center is the tenth. I am 50 feet away [from the target]. I have the gun resting on a soft towel or the gel pad from Pyramyd… This has happened with three pellet guns. Tomorrow I am going to the range to sight in the Shadow 1000 with the BSA scope that came with the Shadow. {It is] a 3-9 scope.”

I told this reader that I thought all his guns were springers because spring piston airguns are notorious for shooting low. Shooting to the left or right isn’t as common, but it does happen frequently. What can be done about it?

Adjustable scope mounts.

What do they do?
Adjustable scope mounts allow the entire scope to be realigned as necessary so that it looks in the same direction as the bore of the barrel. There are two planes of adjustment – up and down and right to left. I have prepared some simple drawings to illustrate this.

Most spring guns have barrels that look down. This illustration is exaggerated so you can see the effect.

The adjustable scope mount has elevated the rear of the scope so it looks in the same direction as the barrel.

Adjustable mounts vs shimming
You don’t have to use adjustable scope mounts to get the required elevation. It’s possible to shim the rear mount (or the rear of the one-piece mount) so that the scope slants down. However, there are limits on the thickness of shims that can be used for this. Adjustable mounts will move more than ten times farther than a shim can move a fixed mount. However, it takes longer to mount a scope when using adjustable mounts. And, unless the job is done right, the scope can come loose after firing. A correctly installed adjustable mount is rock-solid and should remain so for many years.

Adjustments side to side
Adjustable mounts can also move the scope from side to side, to correct those alignment problems. While they don’t happen as often as barrel droop, sideways misalignments are not uncommon.

Looking down from the top, we see that the scope isn’t looking in the same direction as the barrel.

Adjustable mounts enable you to align the scope to where the barrel is pointing.

I should mention that with B-Square adjustable mounts, each ring adjusts independently of the other. So the rear can move up while the front remains stable. That is not true of the BSA adjustable mount. Any adjustments move the entire scope. That’s neither bad nor good – just a different way of doing the same thing.

The B-Square rings are on gimbals, so each is free to move independently. The scope tube will be under no strain as long as you remember to elevate both the front AND rear rings like I described yesterday.

Monday I will show you the BSA adjustable mount in detail. And if you want a look at the B-Square adjustables, you need only ask.