How to get the best "bell curve" with Kodiaks????
I know my gun hates a 3k fill but i need to find a middle ground. Right now i can fill to 3k and set the T.H. at .099 and still get low numbers, less than 800 FPS at the beginning but climbing as the pressure drops. I’m trying to get a decent “bell curve”. Which for me, would be something that starts as close to 900 FPS as possible, rises no more than 100 FPS to 1000 FPS, then falls back to 900 FPS. Now, how to go about finding this without using 1000 rounds of Kodiaks and four trips to the dive shop is the question. I’m thinking about setting the power wheel to 3 or 4 and the top hat to .050 (trying to use the least amount of air as possible) and shooting a 100 string shot count, checking the pressure every 20 shots. If i note the pressure drop for every 20 shots (for instance starting at 3K and say 20 shots later im at 2800psi/40 shots i’m at 2600psi/60 shots i’m at 2400psi etc) if i note what shot number i peak in my velocity (say shot 50=1000FPS) and how many shots i can get after that before i lose 100FPS (20 shots which would be shots 50-70) I would then know not to fill past 2600psi and just check my pressure after i’ve lost the 100FPS. to 900 FPS count the shot count to get there. Wait a minute, after all this mumble jumble i think i just answered my own question. Fill to 3K/Set Top hat to .050/Set Power wheel to 3 or 4. Start shooting, when it hits 900FPS record pressure , keep shooting, when it peaks, record pressure and shot count from the 900 mark, when it drops back to 900FPS record pressure and shot count from peak. What if it never gets to 900FPS??? No problem, just make sure you took a reading at the peak of velocity whatever it was and count the shots from 50FPS from both sides of the peak. You can always go out and open up your top hat more. The FPS aren’t as important as noting what shot number you peaked at and the pressure in the tank. Then you could go back and recharge to 100 psi over your peak velocity/tank pressure and open your top hat to say .070 and repeat the test but only use say 10 shots before you’d know you either needed to open it more or close it down some. Am i onto something here or full of B.S. ?
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Ok, let us know what your results are. I’m signed up to this thread.
Sam, i just got it Friday and haven’t had a chance to shoot over it yet. Plus, I’m hoping the mail-man brings me a new valve today, anyway.
Chad, do you have a chrony? No dumb questions, it’s how we learn.
I’m gonna ask what may seem like a dumb question: Does point of impact deviate noticably when the gun’s shooting on the low side of the curve, versus the sweet spot you’re trying to attain? The reason for my question is more for zeroing the scope. If I zero the scope off the first few shots of a full tank, and I going to see a detectable shift in impact when I reach the sweet spot? I realize that if I do, it’ll settle back down as velocity drops back along with the declining tank pressure. Ultimately, will a squirrel at 40 yards die of a head wound (+ or – .75″ for me) on shot 1 then on shot 20 then again on 35 or 40 with no change in aim point?
All right but i need a starting point for my top hat to begin with. That’s why i was gonna use .050 because i figure i’ll probably shoot a full 100 rounds of Kodiaks doing this test. Then depending on what the max velocity is at .050, i can open up the top hat from there. I wrote it in my notes, but if memory serves, i noted a 100FPS increase per .010 increase in top hat adjustment. I may wind up having to do this test more than once. If i do, the next test will be .070 and a 2500psi fill. I will try to go out today and test it.
start with pw set to middle (6) and a full fill. Shoot until peak velocity is reached. Adjust tophat so peak velocity is where you want it. If it takes more than 5-10 shots to adjust, top off a couple hundred psi every 5-10 shots until the max velocity is where you want it. Top off to full fill and shoot a new string…………..when velocity gets up to where you want your starting velocity remove tank and note remaining pressure; this will be your new fill pressure. Shoot from this pressure (velocity will increase to max then begin slowing down) until velocity decreases back to minimum velocity. This will give you a shot count based on your new starting fill pressure. Fine tune with PW for best consistency/shot count.
Sounds like you are onto something, good job! Now go test it, and tell us what happens.
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hey just to get you started i have mine at .58 gap between top hat and rubber washer, pw at 7 and 2600 psi to 1600 gives me a good curve. i have noticed if you turn the power wheel down to much like 1 or 2 at lower pressure the velosity goes up, my only thought is the valve stay open longer.
because it is slower to open and slower to close, i think other people have had that happen with c02.
hey write down your findings, so someone here can graph it and everyone will be able to use the info, and help someone save some time.