Accuracy at slower velocities - Cayden results with JSB 18s and 719fps

[EPG]

I was testing different pellets at 35 yards with my Benjamin Cayden .22 today. I’ve “tuned” the rifle by shortening the original 3.5” hammer spring to 2.8”. This resulted in improved efficiency and shot count. I now get 50 shots with a 20-25 fps spread. Otherwise, the Cayden is completely stock. One very cool thing about the Cayden (and Akela and Kratos) is the power adjuster knob. This allows a continuously adjustable Transfer Port size. Essentially, the way I set up my Cayden is to adjust the hammer spring tension to shoot my heaviest pellets at my preferred velocity with the power adjuster a full open. Then I can leave the hammer spring alone and just turn the Power Adjuster (Transfer Port) knob DOWN when I shoot lighter pellets - essentially using the “power knob” as a transfer port restrictor. This gives you the ability to shoot pellets at whatever speed works best - WITHOUT having to touch your “tune” of the hammer spring.

Today, I was testing JSB 18.13s and I forgot to return the power adjuster to full open. I had previously tuned the hammer spring to shoot JSB 18s at 865fps. I had my chrono on and saw 719fps on the 1st couple shots - whoops - but both shots went through the same hole. So I keep shooting at 719fps. These are the 2 ten shot groups.

I would have never known that there was an “accuracy node” with this pellet and rifle combo at 719fps if I had remembered to set the power adjuster back to “full open” prior to shooting the JSB 18s. But by accident, I found that you can achieve excellent accuracy & consistency at lower velocities than everyone is shooting their PCPs at these days.

I love my Cayden, .177 Akela and their power adjusters - they make it SO easy to experiment with pellet velocity - much easier than most guns.

 

[Peashooter]

My Maverick shoot redesigns okay under 600 FPS.

Just too bad i dont want to use my airgun as a glorified blowpipe.

 

[davecole]

Congratulations and good for you. Too many believe the faster the gun shoots the more accurate it should be. Nope.

What you are experiencing is “harmonic balance” with the barrel. It’s all the rage if you own an FX. With an FX, you can buy something that dampens the vibration of the barrel when the pellet is fired. If you need to know more about this phenomenon a Google search will lead you down any number of rabbit holes.

This is also why you see carbon fiber sleeves on some barrels and barrels with thicker walls. The more rigid, the less likely to oscillate when you remove, dampen or find the speed which the barrel doesn’t “wiggle” and your groups will tighten up.

My BSA FT gun drills H&N 10.65 @ 860 fps well under the 20fpe rule for HFT. 10fps either side and the groups start to open up.

 

[qball]

Pellets ARE very accurate at lower speed, pellets have upper speed limit but do not really have a lower speed limit when it comes to accuracy. however at lower speed the wind will push the pellets around a bit more hence the perception of slower speed is less accurate, it only means the shooter did not account for environmental. Without wind I can stack pellet at 34 yards all day even at 440fps. 

 

[Corvid_hunter]

X2. Speed does not equate accuracy with pellets.

 

[elh0102]

Sometimes we forget the history of precision accuracy with pellets, 10 meter Olympic rifles at 500 fps.