So this tune I went about backwards for fun I wanted 880 fps and 1/4 from max hammer spring. With fx 25.4 gn pellets. Got velocity set last night ended with 1750 psi at 885. Tonight shot of accuracy at 25 yards one cloverleaf hole. Then moved to 50 yards the target is 3 groups of 3 as I zeroed the scope. I have opened up barrel port as well as transfer port
Air Venturi New tune
- Thread starter imtrigerhapy
- Start date
Just a simple but prolly not simple question. Is it better to have low hammer spring and higher reg pressure as 1750 psi and max hammer get me 880fps as well as 2200 and 3 turns on hammer spring. I also bought the heavy hammer spring with light valve spring but have not put them in yet. At this point in tuning would they help or hinder for 25ish grain pellets.
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I always run everything tuned so hammer spring and valve pressure match nicely. Not one higher or lower significantly than the other. For the chosen reg pressure start with a very low hammer setting and ease it up until no more velocity increase can be had then back it down slightly. This should match the two evenly and give a nice shot cycle.
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I learned that the formula of 95 comes into play when tuning.
If you are looking for a velocity of 895 fps:
895 / .95 = 942 FPS.
So, turn your hammer spring in all the way and adjust regulator until your velocity hits 942 fps. Then back out the hammer spring till you hit 895.
This way you won't waste air. The valve should be closed before the pellet/slug reaches the end of the barrel. (Dwell time)
Your tune:
880 / .95 = 926 FPS
Good Luck!
If you are looking for a velocity of 895 fps:
895 / .95 = 942 FPS.
So, turn your hammer spring in all the way and adjust regulator until your velocity hits 942 fps. Then back out the hammer spring till you hit 895.
This way you won't waste air. The valve should be closed before the pellet/slug reaches the end of the barrel. (Dwell time)
Your tune:
880 / .95 = 926 FPS
Good Luck!
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I can get my Maverick ( 700 mm ) up to the speeds i like with a mere 60 - 70 Bar, but for some reason it shoot better with a 80 - 90 Bar pressure.
And trust me i have tried jumping thru all kinds of hoops to try and make the rifle perform at the lower pressures, but i just can not make it perform as well.
I tend to start with a low pressure and low hammer, and then increase hammer, and if that do not work i give it a little bit more pressure back the hammer all the way back and start all over.
I tend to jump pressure in 10 Bar segments, but i might get lower than that now i have a digital gauge for my regulated pressure.
And trust me i have tried jumping thru all kinds of hoops to try and make the rifle perform at the lower pressures, but i just can not make it perform as well.
I tend to start with a low pressure and low hammer, and then increase hammer, and if that do not work i give it a little bit more pressure back the hammer all the way back and start all over.
I tend to jump pressure in 10 Bar segments, but i might get lower than that now i have a digital gauge for my regulated pressure.
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My mav and wildcat BT neither work that way well. Whatever reg pressure I run if I tune the gun right up to nearly the max velocity it will produce with that reg pressure they shoot awesome. Extreme spread of 10 or less. Once I start to tune down from that spot the ES goes up to 20 fps rather quickly. Guess I get a little picky about ES maybe.
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