Scope mount basics – part one

by B.B. Pelletier

A lot of airguns are scoped these days, so I thought it would be nice to cover some of the basics about scope mounts and rings. With airguns, more often than with firearms, scope mounts and rings come together as one unit. While firearms have separate bases called mounts that attach to the rings, most airguns have their bases installed on the guns, so the rings are made to fit to these guns.


Get this handy scope-mounting catalog direct from B-Square.

B-Square set a high standard for airgun mounts!
The most common scope-mounting base found on an airgun is an 11mm dovetail, but you need to know that gun manufacturers have not always adhered to that dimension as close as they should. B-Square publishes a free brochure about mounting scopes on airguns, and they have a chart that shows airgun mount bases range between 10.6mm and 14.1mm, so you can expect some deviation from gun to gun. Get this free brochure by calling B-Square at 800-433-2909, 8am-5pm (Central time), Mon-Fri. Ask for customer service.

Scope rings with built-in mounts have to span a wide range of sizes to clamp to a gun. Once again, B-Square is the leader is designing mounts that fit a wider range of airguns, plus they make special-purpose dedicated mounts for guns that vary by too much, like BSA.

Stopping scope ring slippage
If your gun recoils, you need a scope stop. NO AMOUNT of clamping pressure alone can hold a scope mount on a recoiling airgun. There must be a positive stop to arrest rearward motion, or the mount will back right off the gun. Some rifles such as the Webley Tomahawk have only the rear runout of their dovetails for this function. It’s not the best way to do things, but the Tomahawk doesn’t kick enough to make it a problem. Just be sure to back the rear mount (when using two-piece rings) or the rear of the one-piece mount completely to the end of the dovetail cuts so they can grab the mount when it tries to back up.

Most guns have holes or notches to arrest the mounts during recoil. The scope stop pin goes either into the appropriate vertical hole or the cross slot on the receiver. The stop pin can be part of the rings or a separate item. B-Square makes a special scope stop for the Webley Patriot because its stop notches are quite different than those found on most rifles.

Weaver and Picatinny mounts won’t work for airguns
Neither of these fine mount-locking systems work on airguns as they come from the factory. B-Square makes an 11mm to Weaver adapter that turns a simple 11mm dovetail into a Weaver base. If you already have Weaver rings, you need this adapter.

There’s more to talk about, but that’s a good start. I’ll get back to scope mounts and rings very soon!

22 thoughts on “Scope mount basics – part one

  1. I have never tried B-Square mounts but BKL mounts are “the standard” in field target. Their mounts are made from solid aluminum and are easy to remove from the gun and replace with virtually no change in POI. They make reach-forward mounts that solve problems with fitting long scopes on a short mounting area, too.

    I shoot PCP but have heard that the piston people fid they work great without a stop (albeit most piston shooters are using TX200s).


  2. Joe,

    BKL mounts are the ones I noted as slipping on a springer. I crushed a Beeman R9 spring tube while tightening a set of BKLs and they still slipped. The mounts were clamped so tight the mainspring was binding when the gun was cocked.

    They are fine for PCPs, but for recoiling guns, I still believe a positive stop is needed.

    B.B.


  3. I DON’T THINK MUCH OF B-SQUARES DESIGN ON THEIR MOUNT FOR THE TOMAHAWK RIFLE. THEY USE TWO SMALL TANGS TO FIT INTO THE DOVETAIL. THIS DOES NOT PROVIDE MUCH HOLDING POWER. I PUT ONE OF THESE ON MY TOMAHAWK, AS FAR BACK IN THE GROVE AS IT WOULD GO, STILL LETTING THE TAB SINK INTO THE GROVE TO THE FULL DEPTH. I SIGHTED THE RIFLE IN AND IT WAS SHOOTING FINE FOR ABOUT 20 SHOTS. I THEN NOTICED SHOTS STARTED MOVING TO THE RIGHT. EVERY SHOT I FIRED WOULD PROGRESS FURTHER TO THE RIGHT. I EXAMANED THE MOUNT AND FOUND THE SMALL TANG WAS WORKING ITS WAY OUT OF THE DOVETAIL AND THE ALUMINUM MATERIAL OF THE BASE ON THE OPOSIT SIDE WAS BENDING ITS WAY OUT . MY TOMAHAWK HAS A WALNUT STOCK, SO IT IS LIGHT. THIS GUN SEEMS TO HAVE A VERY SHARP, QUICK RECOIL. I THINK I’M GOING TO APPLY A SMALL AMOUNT OF EPOXY TO A GOOD RECOIL STOP NEXT TIME I MOUNT A SCOPE ON THIS GUN, EVEN IF THE STOP BECOMES PERMANENT.


  4. Dave,

    I sympathize with your problem, but B-Square shouldn’t get the blame. At least their mount is aluminum, so it won’t tear out the dovetail of your rifle!

    Webley should put a positive recoil stop on this rifle. It is so nice in all other ways, I have never understood why they don’t fix this problem.

    I hope your planned fix works.

    B.B.


  5. DO YOU KNOW IF THE METAL ON THE TOMAHAWK SPRING CHAMBER IS THICK ENOUGH TO MACHINE A ROLL PIN HOLE FOR A SCOPE STOP? THIS TUBE SEEMS JUST SLIGHTLY THINNER THAN THE ONE ON MY BEEMEN RX-2 JUDGEING FROM OUTSIDE APPEARANCE AND THE RX-2 HAS THESE HOLES.


  6. I wouldn’t try cutting through the receiver tube on your Tomahawk. I believe the steel mainspring is operating on the other side and would give you problems if a pin passed through the tube.

    B.B.




  7. Recently I received a Daisy Electronic Sight Scope for a daisy-red ryder. After installing it on the bb gun, the scope appears foggy and there isn’t very much contrast when looking through the sight to see the target very well. do you have any idea what we must be doing wrong or what the problem might be? Also, do you know where we can find info on how to calibrate the laser scope.


  8. Ben,

    What you have is a red dot sight. It is supposed to look like you are looking through a clear window. There is no magnification. When the red dot is turned on it should appear in the center of the window, when you hold the BB gun correctly.

    You can adjust the dot so it rests on where the BB goes, but since BBs are not very accurate, this will only be a general area.

    B.B.


  9. GAMO cfx solves the sliding scope problem very very well. They have a 4″ long riser bar that has about 5 bolts, very secure. It is drilled for the rear scope ring’s set screw. The riser bar is also mounted to the gun with a set screw. The scope rings use Torx screws for clamping. I remember my first gamo rifle. I expoxied a weaver rail to it, and the scope hit me in the head after a hundred shots, breaking off and ruining the shot. This CFX scope does not move, even with a laser/light attached! But I love the target sights. I think I will go back to them in the summer.




  10. im 11 and i have a daisy red rider. i was wondering if i could get a bipod for when i am laying prone and when i am shooting long range. if you can, please include the name of the bipod and the price.



  11. this isnt really about scopes but hey, i might as well ask. can i use airsoft bbs in my daisy red ryder? i was just asking because my parents are kinda nervous about metal bbs and plastic is cheaper. ( $8.99 for 2,500 metal bbs vs $9.99 for 6,500 plastic.)


  12. No.

    Airsoft "BBs" (they are NOT real BBs) are 6mm in diameter and steel BBs (the real BBs) are 4.3mm in diameter. As you see, there is a huge difference in size.

    The airsoft BBs are only called BBs because the Asian makers of the guns don't know any better. To them, any spherical projectile is a BB.

    B.B.


  13. I have a break barrel air rifle with a scope on it. When I shoot the recoil cause the scope to slide back in the mount rings. Is there anything I can do about this? Thanks


  14. Philip,

    AirForce Airguns has a compound that will stop the movement. I don't know if they are ready to sell it yet, but you can call them at

    877-247-4867.

    I understand that plain old rosin will work, too.

    B.B.



  15. Re: scoping a Red Ryder – You can make your own scope mount with PVC without using glue – see CHFTN55 on FLICKR for a setup on a Marlin Cowboy or try to find a Brice/Crosman Red Ryder Scope mount – hard to find.


  16. How to Make a Scope Mount for a Marlin Cowboy/Red Ryder or Similar BB Gun

    1. Measure the space between the base screw at the top of the stock and the middle of the slotted open sight.
    2. Take a standard PVC pipe and cut it to that length.
    3. Cut the PVC pipe in half, very carefully, and sand the bottom to even.
    4. Sand the inside of the half-pipe to fit the contour of the top of the gun, using either a Dremel, or a sanding block, very carefully.
    5. Fit the half-pipe as sanded under the open sight (removing the adjusting piece) and mark hole spots over the base screw and the slot in the sight.
    6. Drill and bevel the holes, making sure they are on the same line so the scope will be straight on the barrel.
    7. Remove the open sight, and bolt the front end of the PVC to the sight slot, bolt up.
    8. Remove the base screw, and then screw the back end of the PVC to the top of the gun, careful not to strip the wood.
    9. Place the scope on the PVC and carefully mark where the scope rings will be, after you have determined the best eye placement for you.
    10. Cut 3/8 parallel slots in the PVC where the scope rings dovetail, making sure you have the scope straight on the barrel. Tighten (PVC is good for this).
    11. Sight in the scope at between 5 and 10 yards, and have fun.

    Pictures of such a handmade scope mount on a Marlin Cowboy can be found on FLICKR under the moniker “CHFTN55”


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