Going to copy and paste a somewhat detailed, yet hopefully simple explanation of this from another thread. I had the exact same issues and got great info from people here and have been able to get things working proper after tuning. I can almost guarantee your issues come from having the slug power kit installed. The 13g hammer weight is really made for higher reg pressures and getting top end speed for heavier slugs. If your power wheel is not showing max speeds on PW7, then it is simply overpowering the valve. At 135 BAR, my Maverick would do the same thing until I had the hammer adjuster turned in to 0mm. If you want to shoot lighter weight stuff along with the heavy, then you probably need to take your reg 2 pressure up to 140ish to start. Adding a slight bit more pressure (5 BAR or so) once you find your target velocity (and the power wheel works as intended) will stabilize your ES.
I will try to explain it from my understanding and as simple terms as possible. These hammer operated airguns are what we used to call "balanced poppet valves". It is balanced because you are basically trying to balance the air pressure that comes thru the reg against the strength of the hammer strike that opens the valve. The valve is actually held closed by pressure, so if you increase the pressure from the 2nd reg here, then a properly tuned gun will actually show a decrease in velocity because the spring and hammer are not hitting hard enough to overcome the increased pressure behind the valve.
Tuning to the knee would be taking a set pressure and working your way up or down the hammer tension until it reaches a plateau (the knee). Come from the paintball world, we typically always worked up…..but airgunners seem to generally max everything and work down. If you are trying to make sure you are able to hit a maximum level of energy I can see that being the way to go. If you are tuning for moderate numbers or for pellets, my thought is to work up.
When you start low and work your way up in tension on the hammer (micro and macro wheels) you will hit a spot where velocity stops going up and further increases in spring tension will make the velocity drop. If you are in your target range for velocity, you can then back the hammer tension back to the plateau and then go about 5% past that down. That would put it at a lighter strike of the hammer and a more efficient tune as well.
If you cannot get into your top end velocity target with where you are at with that reg setting, then you may have to increase the reg setting start again in finding your knee.
I will try to explain it from my understanding and as simple terms as possible. These hammer operated airguns are what we used to call "balanced poppet valves". It is balanced because you are basically trying to balance the air pressure that comes thru the reg against the strength of the hammer strike that opens the valve. The valve is actually held closed by pressure, so if you increase the pressure from the 2nd reg here, then a properly tuned gun will actually show a decrease in velocity because the spring and hammer are not hitting hard enough to overcome the increased pressure behind the valve.
Tuning to the knee would be taking a set pressure and working your way up or down the hammer tension until it reaches a plateau (the knee). Come from the paintball world, we typically always worked up…..but airgunners seem to generally max everything and work down. If you are trying to make sure you are able to hit a maximum level of energy I can see that being the way to go. If you are tuning for moderate numbers or for pellets, my thought is to work up.
When you start low and work your way up in tension on the hammer (micro and macro wheels) you will hit a spot where velocity stops going up and further increases in spring tension will make the velocity drop. If you are in your target range for velocity, you can then back the hammer tension back to the plateau and then go about 5% past that down. That would put it at a lighter strike of the hammer and a more efficient tune as well.
If you cannot get into your top end velocity target with where you are at with that reg setting, then you may have to increase the reg setting start again in finding your knee.
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