B-Square adjustable scope mounts – Part 1
by B.B. Pelletier
B-Square founder, Dan Bechtel, was the party responsible for their entire line of adjustable airgun scope mounts. He had looked at various other adjustables and decided that none of them were right. Some of the most expensive European mounts even failed to compensate for the misaligment of the two rings when they adjusted, resulting in strains that dented and broke scopes.
Before making his first mount, he undertook to measure the width of the dovetails of all airguns, and in that study he discovered there is very little standardization among airgun manufacturers. He found dovetail widths that varied from 9.4 mm to greater than 13.5 mm – all under the umbrella of the “11 mm” dovetail. He also discovered no standardization of the dovetail angle – with some cut at 45 degrees and other cut at 60 degrees. Only the angles of common cutting tools kept the variance that small.
But a bigger problem was how to ease the strain on the scope tube when the two scope rings were not in alignment. By the very nature of their adjustability, they were guaranteed to never be in alignment.
The resulting product was B-Square’s AA Adjustable scope ring. Though only the one-piece design still uses that product terminology, the design of both one- and two-piece mounts is essentially the same today. And these rings are so flexible they can almost scope a banana!
At the heart of all B-Square adjustables is a gimble support system that holds the scope rigidly even though the rings may be in different planes both for elevation and left to right. Gimbals are those marvelous multi-axis supports that allow objects like ships’ compasses to remain level even when the vessel they are attached to moves in all directions beneath them.
When the scope is not mounted, the rings flop around like limp noodles, but once the ring caps are tightened on a scope, they become rigid, as long as all screws are properly tightened. They use the rigidity of the scope tube, itself, to make the mounts stable.
How it works
A steel split ring is held inside the bottom of the scope ring by two opposing adjustment screws, This ring is threaded on a steel post that comes up from the scope base. The adjustment screws act as bearings, allowing the ring to tip back and forth.
You are looking at the bottom of a scope ring flipped upside-down. This steel split ring threads onto the stud that sticks up from the mount base. There are two holes on opposite sides of the split ring that the noses of the two small adjusting screws enter, allowing this ring and the scope ring attached to it, to swivel back and forth. This is why the scope ring will tilt when the scope tube changes its elevation.
The steel split ring threads onto this stud. The stud can be any height, allowing owners to have both high and medium-height rings in the same package. All it takes to make the change is an inexpensive optional riser stud.
This is the actual steel split ring. You can see one of the opposing holes that the noses of the adjustment screws enter. Notice the half-cut on the opposite side of the split to allow the pressure from the adjustment screws to squeeze the split ring closed. This is a new style split ring, while the first photo shows an older style.
And here is the entire assembly, right side up. The oversized hole at the base of the ring allows it to be adjusted in all directions.
You can now see how these mounts work. For side-to-side adjustments, the two opposing adjustment screws are adjusted. When the split ring is pushed to one side of the enlarged hole in the base of the scope ring, the scope ring, itself, moves in the opposite direction. Because both front and rear scope rings are adjustable, there is a lot of adjustability available.
For elevation, the scope rings are turned on the threaded post. They can adjust in both directions, but at the bottom the ring will impact the mount base and stop turning. At the top the ring will screw off the threaded stud .
One very common mistake people make when installing these rings is they allow the adjustment screws to pop out of the holes. When that happens, the rings will never get tight, regardless of how tight the screws are.
We are not finished by any means. I have not covered function, nor how to make adjustments, so please stick around.