New Talon SS .22 Chrony Results
I started with a 2700PSI fill pressure and after about 20 shots I was down to 2500 with the powerwheel set to 1. I was shooting JSB Exact Jumbo Express Diablos that weigh in at 14.35gr… I had the PW set to 3 before the test, but the velocity was at nearly 870, so I decided to take it down to 1 on the PW. Are these highly variable results typical with the PW set so low, or is my gun just weird? All 20 shots fit into a dime size hole at 15-20 yards, with very little effort.
All Replies
Sounds good. I’ll have to do some testing tomorrow I guess. It’s just so damn accurate at 25 yards (furthest I’ve tested) that I don’t want to mess anything up. Hopefully, I can figure out which PW setting works best tomorrow.
ok, I can understand your apprehension about the top hat. In that case the best you can do now is fill to 3000 psi and find this “optimal” (I like to say magical) PW setting. Start from PW = max and shoot a string. My bet is that you will get a very high FPS, then each and every shot will drop more FPS. Obviously you don’t want that! You want somewhat of a bell curve, not too much though. Continue dropping PW by 1 and get a string. If you could post that info for me, from PW = 1,2,3,4….12, make sure you record ending pressure (although it might not be accurate because of your bad pressure gauge!) Then we can go from there and fine tune it…
I wouldn’t pay much attention to the PA guy. Try it at 3000psi and you’ll see that I know what I’m talking about.
I’m a little apprehensive to adjust the top hat at the moment, since I don’t want to mess anything up… with that said, should I be good to go by just filling up to 3k and then doing a chrony run with the PW at a higher number?
your top hat is adjustable. There are two set screws that you simply loosen, then you can turn it either CW or CCW. Turning it CCW will increase power as the hammer will strike it with more force. (obviously CW to decrease power). You don’t need a feeler gauge. Simply start from where it is “flush” then turn 1/4 turn from there until you achieve the velocity you want. IMHO, JSBs are overrated. I would recommend you look at H&N Baracuda Match.
I wouldn’t pay much attention to the PA guy. Try it at 3000psi and you’ll see that I know what I’m talking about.
My TSS has a high flow valve with a weighted hammer. I do not overcome valve lock until the pressure drops to 1800 psi. That is my fill pressure. Anything above that and performance drops drasticly. It is a very rare AF rifle that will not experience at least some valve lock at 3000 psi. You will need a chronograph to determin the optimum fill pressure, but most work well with 2700 psi. Use the pump gage. Yes to the feeler gage.
Utter, utter nonsense.
The guy I talked to from PA, told me to use the 18gr JSBs at 2600 and refill at 1900PSI. Top hat gap of .08 to .09 (whatever that means), and PW to 3 to 4… with a goal of 750-800 FPS. I don’t have 18gr JSBs on hand, so I don’t know what kind of velocity to shoot for. Do you use feeler gauges to determine “top hat gap?”
According to the spin-loc tank I filled it up to 3000, but my hill pump shows 2700. should i just go off the hill pump and add another 300 psi and try again?
Speedy, listen to me I know what I’m talking about. The pressure gauge on the airforce tank is CRAP. Go by what your hill pump pressure gauge say. Always pump to 3000 psi.
Utter, utter nonsense.
According to the spin-loc tank I filled it up to 3000, but my hill pump shows 2700. should i just go off the hill pump and add another 300 psi and try again?
always fill to 3000 you get the best results that way. It’s the way the hammer / valve was designed for.
- You must be logged in to reply to this topic.
Actually, your string looks like mine when it’s on the edge of valve lock. (~3200) You should try an o-ring behind the tophat. It narrows the gap and eliminates valve bounce. When the hammer strikes, the metal tophat slams the metal valve body and rebounds, causing short valve opening duration. High pressure in your tank is trying to push the valve closed, and the bounce is enough help to crash performance. It’s also an unstable situation, so mostly what you see is weird behavior. Also, a low power setting causes a similar problem because the valve opens less and so is more readily slammed shut by air pressure.
Tophat gap adjusts the valve stroke, and thus the valve cycle duration. An o-ring narrows the gap, but by eliminating the bounce, it’s break even, or maybe even improved performance. Your tank pressure determines the useful range of the power wheel, since more hammer force is required to cycle the valve at higher pressure. At 3000psi, it takes more hammer force to cycle the valve reliability. If you want to reduce velocity, you need to drop pressure. Some folk are shooting .22 under 2000psi. At low pressure, valve bounce is more of a problem since the tank pressure resists the hammer strike less. (Resistance slows the hammer, reducing bounce. Less pressure, harder hit.)
Thing is, AirForce guns have a steep learning curve because they’re so adjustable. I spent hours shooting long strings and taking notes as pressure dropped. JSBs are good for this since they are stable in a wide velocity range, so eliminating one of many variables you’re dealing with. Eventually things will begin making sense.
The power wheel is really for fine tuning. In the manual, AF notes that you should waste a shot after adjusting the PW, to settle the action. And that’s God’s own truth. I was determined to figure out a way to adjust power as pressure dropped. Ain’t happening. Your easiest adjustment is tank pressure, and you’re too high. Next is the tophat. Get past your hesitation, it’s not tricky. Just grab a set of automotive feeler gauges and select a stack that provides the proper thickness and have at it. Just don’t overtighten the setscrews as you can dent the stem. I opted for a Talon Tunes one-piece tophat. Radically more complicated to tune with the inserts and completely worth the effort.
Sounds like the PA guy was on the right track, just add an o-ring and have fun!
John