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Education / Training B-Square adjustable scope mounts – Part 1

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.

author avatar
Tom Gaylord (B.B. Pelletier)
Tom Gaylord, also known as B.B. Pelletier, provides expert insights to airgunners all over the world on behalf of Pyramyd AIR. He has earned the title The Godfather of Airguns™ for his contributions to the industry, spending many years with AirForce Airguns and starting magazines dedicated to the sport such as Airgun Illustrated.

20 thoughts on “B-Square adjustable scope mounts – Part 1”

  1. hey BB i have a question, i have a kodiak .22 and could never get better than 2 inches at 50 yards, i had an bushnell 3200 scope on it. i took the scope off of it and went back to open sights thinking that it may have been the scope. by the way i shoot cp’s and field target specials. accuracy went down slightly because of open sights about 2.5 inches at 50. i went to clean the barrel and the brush went through smoothly.

  2. then i put in a pellet and pushed it through with a cleaning rod, and i noticed that it was tight ant the breach got easer after about 3 inches, witch may have been the pellet taking the rifling then about half way down got hard for an inch then easy the rest of the way. is this normal. i have cleaned the barrel reguary. and can shoot better with my r1 and hornet. ps if you look in the barrel it looks smooth. thanks

  3. Hey BB,

    My 17101 with the BSA 3-12x44mm just doesn’t stay put on the Webley Xocet. I crank those 4 bolts at the bottom down to as tight as I can without fear of stripping/snapping the bolts, and it will still walk ~1/4″ back per 100 shots or so. I set it back up with open sights for now, but I have to figure out something. Any thoughts?

    -David in fla

  4. David,

    No amount of clamping pressure, alone, can prevent a scope and mount from slipping on a spring rifle. Unfortunately, Webley never put a positive scope stop device on many of their rifles, apparently believeing that clamping pressure alone would stop the movement.

    The only thing I can say is to back the scope mount up to the rear of the dovetails and hope they will hold, but from experience I know they wont. Your rifle needs some kinde of vertical hole for a scope stop pin to enter.


  5. Kodiak,

    I just figured out that you left two comments. So, yes, what you felt was normal. You have a rough spot in your barrel at that point. Cleaning with JB paste will pprobably remove it.

    Most barrels look shiny and smooth. Looks are unreliable. When you clean with JB paste, be sure to use a brand new bore brush.

    You say that you clean the barrel regularly. I hope not with JB paste! You only have to clean one time with JB, unless you keep shooting Premiers. Then you need to clean each time accuracy falls off.


  6. Just a bit of my experience to add to today’s helpfull blog.

    I’ve found that with the B-Square 17101, by removing the top half of both scope rings and using a lighted magnifying desk lamp, I can easily align the dimples on the split rings with the points on the grub (set) screws. This also helps me approximate and center the bottom half of the scope ring. Once you get all the parts “floating” properly, it takes very little torque to clamp down the rings.

    Once set up correctly, there has been 0% movement on my RWS Mod 34 after hundreds of shots. I do admit that I rushed setting up the first 17101 that I purchased, but B-Square was happy to replace the parts I stripped with no questions asked.

    I did also clean the parts carefully with denatured alcohol right out of the package. This helped tremendously. This is a great product for droopers!

    Paul Capello

  7. Hey, B.B. I figured you would get to it in the next report on the AA’s. Again, it was by your reccomendation that I got the B-Square in the first place when I purchased the mod.34. I’m still an airgun newbie, but you’re schoolin’ me!

    -Paul Capello

  8. Re the problem with scoping a Webley…. I had trouble with my Longbow, the rail being a little on the wide side and so offsetting the scopemount a bit, which didn’t seem to line its gripping edges too well with the rail.
    Sorted now – a pair of double-strap BKL model 263 mounts (nominally 11mm) at what seemed to be just about the absolute maximum of their mounting expansion do fit the rail neatly…. and grip very, very tight.
    If it’s the same rail width is used on the Xocet, then BKL mounts could be worth a try (double strap to give more grip area).

  9. Brit Visitor,

    That’s really good to know, because I have several people who have been looking for a solution. If I understand what you are saying, you mounted the two BKLs in tandem? And that gives you four rings?


  10. BB –
    I just ordered a 3-9×50 center point scope from pyramid based on their recommendation. I didn’t see any info on your blog about it but I thought I remember seeing a post here somewhere about centerpoint saying they’re fine – any comments about it?

  11. Thanks BB – your blog has been very helpful for bits and pieces of info to make informed decisions for sure. Pyramid suggested the one piece mount like you suggested, so I will give ‘er a go and report back if my hands are steady enough.


  12. brit visitor,

    You’re exactly right about the rail on the webley being wider than the Bsquare mount. I put some #8 lock washers between the two pieces of the base to give it a little more spacing in hopes to get an even clamping force, but it looks like it’s still a bit of a parallelogram if you know what I mean.

    I think I’ll give the BKL’s a try. Did you use the D7’s for the .007 droop on your webley? Mine has a bit of droop, so I figure those would be best on a non adjustable rail like the BLK.

    Thanks for your input all!

    -David in fla

  13. “If I understand what you are saying, you mounted the two BKLs in tandem? And that gives you four rings?”
    No, just two mounts… that BKL pair differ from most mounts in that (for each mount) across the top of the scope there are two separate half-rings, each of which connects with one screw per side, to a single base piece.

    ie. a total of 2 base units, but a total of 4 straps across the top of the scope.

    The base units are spaced apart on the rail just as they would be with any other make of mounts.

    “Did you use the D7’s for the .007 droop on your webley? Mine has a bit of droop”
    There was no apparent problem of droop on my Longbow, and I could use the 263 mounts ok – vertical zeroing fell safely within the adjustment range of a 1″ tubed 3-9×40 mildot scope.
    Don’t know about BKL’s droop compensating mounts; the availability of BKL mounts is not very good (and they’re rather expensive) in Britain – so I bought mine via the internet from the USA.

  14. Begging forgiveness first, this post is a question not related to this blog. I didn’t know how else to ask this question. You seem to know all about the Benjamin Franklin air pistols and I have one I’d like to sell. It doesn’t look like the one you blogged about in a post two years ago and I’m hoping for some more help in the ID on it?


  15. Kim,

    Anyone can ask about anything at any time on this blog.

    Tell be something about your Benjamin. Remember, Benjamin Franklin is a company joke – not a real name. That’s why it is in quotes. In the English language, things that are not true are put in quotes.

    On the end cap that you look at when you hold the pistol there should be some numbers. If not there, then somewhere on the side of the gun – right side, usually.


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