Air guns

Low cost scopes modified to survive the Magnum Springers.

By. Brent R. Shepard 

DISCLAIMER: The results I will be speaking about are the results I get with my equipment ( scope, gun, Chrony, and pellets) your results may vary even if using the same equipment.

GOAL: To find a low cost scope combination that would be accurate and survive the forces associated with a Magnum Springer.

BACKGROUND: I am not new to air guns, but I am new to magnum springers. I did my research and settled on a B21 (.177) as my new gun. Prior to receiving the gun I read many posts on many forums, I quickly came to realize there were 2 major things I would have to do to this gun. The first would be to disassemble, clean, and inspect, then when that was completed, modify the gun ( I did many modification to this gun and I believe I see incremental increases in my power, accuracy, and reliability. Adding these efforts to this summary would not add any value, so I will omit those efforts). The second was installing a scope ( I am a poor shot, I need a scope to get any pleasure from the sport), but most posts I read said, I would have nothing but problems if I used a scope on a magnum gun. I was not willing to pay for the scope setup that was recommended for a magnum, in the end I would of spent more on the scope that I spent on the gun.

FIRST TEST: I bought a Tasco 3-7X20 scope at Walmart for $19.99. I prepared the gun using a solvent to clean the scope rail, I also used the solvent on the scope tube and clamps, I then scratched the scope rail and scope tube, I then used epoxy to glue the clamps to the rail and the glued scope in the clamps. I did this because everyone talked about scope creep and I didn’t want to weld these things together. I believe, using a good epoxy, making some scratches (where epoxy is to be applied) would have almost the same effect as welding. NOTE!!! If you do this, realize you may not be able to get the scope off in one piece.

FIRST SHOTS: I had 40 different types of pellets I decided to test in my back yard @100 feet. I got to pellet type #25 and stopped ( it was getting cold). Later that evening when reviewing the paper targets I detected a greater variance horizontally that vertically in 20 types out of the 25 ( non random pattern). I went to 3 different forums asking for help in diagnosing this. All the suggestion were unique, I tried all of them ( most had to do with hold), none of the suggestions really helped, although on more than one occasion I was told to look at my scope.

Benjamin Sheridan Diablo 7.9 gr RWS super mag 9.5.  FPS avg. 941 9/16 V. grouping FPS avg 880 7/16 V grouping


Crosman 7.9 gr pointed Crosman 10.5 premiere.  FPS 982 ½ V grouping FPS 828 ¾ V grouping

These are just 4 examples of the grouping problem I had.

I decided to revisit my scope, I used liquid nitrogen to break the epoxy between the clamps and tube, I rotated the scope 90 degrees counter clockwise ( up/down is now left/right and vice versa) and shot some more.

Much to my surprise, the grouping was the same, I was at a loss and ready to give up.

I didn’t and decided to try one more thing, I rotated the scope to 45 degrees of original, and did some shooting.

Now I really became confused, I was getting a truly random pattern (or so I thought) but the variance of my now 20 random shots was equal to my horizontal variation. I said to my self “ Self, what now” and self said “Hee Hee Hee it’s time to start drinking”, so I did.

While reviewing the paper target (and drinking) I detected what I thought was an “X” pattern. So the next morning ( when the cob webs cleared ) I went and shot 50 shots on blank paper, and there was truly an “X” pattern.

I took the scope apart ( to investigate ), and found a single spring was driving the light pipe in to the 2 adjusters. The light bulbs started going off now. The kick of the gun when firing always kept the light pipe in contact with the up/down adjuster but would allow the light pipe to move left/right, sometimes not returning to its starting position.

This is how I believe I have permanently resolved this, thus allowing cheap scopes to be used on these magnum springers.

THE FIX: I drilled and tapped 2 holes in the scope tube ( opposite the adjusters ), and used 2 stainless steel pointed screws to drive the light pipe in to the adjusters. I tightened all optics and used a speck of super glue on these threaded optic rings, I used lock tight on all screws ( adjuster body and light pipe anchor) and re epoxy the scope tube in to the clamps ( see pictures).

SECOND SHOTS: Out standing, I’ve enclosed some of the targets, BUT these were not shot at the same conditions as the first ones. These were shot at 113 feet ( from my kitchen to my target pit, inside temp 74 outside temp 50, and this time of year in New England there is always a wind. So the first shots were under the best conditions and the second shots were under worse conditions.

Crosman 7.9 pointed.   Crosman 7.9 domed.   Crosman 10.5 premiere

I completed my pellet testing this day too. After ALL that shooting Crosman still seemed to group the best.

Here are some pictures that are similar of my Tasco scope




FINAL NOTE: I believe this should last a long time because, the Tasco scopes flex point is all metal, there are 3 anchor point screws, and I tightened all optic clamping rings the dabbed super glue on the threads.

BUT only time will be the true judge. If I have to change this scope (due to damage), I would rather be spending $19.99, not $250.00 on a scope that according to some posts may be damaged by a magnum springer.

Happy Plinking All


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