Probably the most common question I get from owners of the Leshiy is how to tune the gun to get the most power, best efficiency, and tightest extreme spread possible; the holy trinity of airguns so to speak. Before arriving at the adjustment explanation part of this blog, I feel it is essential to understand how a regulator works. The part that is commonly called the regulator is made up of three main components: the regulator, plenum, and the valve housing. The regulator steps the pressure down from the air reservoir, fills the plenum with air that is "regulated" and then sits on the valve ready to send a pellet down range when the shooter performs the simple act of pulling the trigger. It is safe to estimate that about 85% of the speed is determined by the regulator setting and plenum size with the remaining 15% stemming from an adjustment of the hammer spring.
The hammer spring is merely a spring that sends the hammer crashing into the valve. How fast that hammer smacks the valve determines the travel of the valve; this is known as valve dwell time (VDT). The longer it is open (to a point) the more regulated air will escape the plenum and the faster the pellet will travel.
It is important to note that the regulator and hammer spring together will have two bell curves regarding the speed of the pellet. These are the first peak and the second peak of the regulator. As the user turns the hammer spring tensioner (HST) delivering more compression in the spring, the speed will rise. Continue to increase spring tension without changing any other settings and the speed will "peak", then begin to fall. If the spring tension is increased further a speed rise will be noted again before collapsing on the second bell curve. This drop in speed is commonly called the second peak, and it is less efficient and less consistent when compared to the first bell curve. The reason for these two bell curves is merely a result of over compressing the spring. Think of it like throwing a punch at different distances. Too close or too far away, and it won't hit hard. At a point, the spring has less speed because of high compression; this lessens the VDT.
The speed peak of this first bell curve is what we are looking for when tuning a gun. Some parts of the tuning process is a hunt and peck when a specific speed is sought, and the user is looking for the hammer spring and regulator to be in the balance that will deliver the perfect VDT. Remember the spring needs just the right amount of travel to strike at the same high power to the best consistency. Every spring has a different operating range of power stroke.
The second part of the speed equation is the regulator setting. It is incorrect always to make a correlation between speed and a higher regulator setting. Sometimes if the plenum and transfer port are correctly sized a lower regulator setting will result in more speed. A lower regulator setting may increase speed because the valve has less pressure on the top of it, and as a result, the valve is free to open more and exhaust the plenum more easily.
With the Leshiy equipped with the Huma regulator and plenum, a good starting point is 110 Bar. From this point, the user can find the peak with each caliber by turning the HST up (counter-clockwise) until the speed decreases. The tuner will record the highest speed for the chosen regulator setting before the speed falls. Once the peak of the bell curve is found then the best procedure is to shoot the gun approximately 10-15 FPS slower than the number recorded from the highest speed. This will allow the gun to be shot with the most exceptional consistency and shot count. Setting a Leshiy in this manner will enable the gun to be shot 10 bar lower than the regulator setting and still maintain point of impact.
In closing, the process may be slightly time-consuming, but the performance increase will make the time spent adjusting the HST and regulator a rewarding experience. There are slight differences between calibers, and some calibers might need a higher regulator setting than expected. The .177 is one caliber that might require the regulator setting to be higher because the barrel is small when compared to the transfer port. This causes a "throating effect" and the gun may need a short, quick burst of air. This higher regulator setting does not decrease shot count. Instead, the valve will not waste air and will deliver a short, sharp burst of compressed air, moving the pellet most efficiently.
Feel free to post any questions or comments.
-Brian