valve frustration
Talon SS
Stock hammer
stock spring
new breech
stock .177 and .22 barrels
new AF talon valve
I am having issues where I am having to use a fairly high amount of preload on the spring like 8-10 to get it to fire reliably as well as varied velocity 550 fps up to 900.
yes I have used fill pressures anywhere from 2000-3000 PSI
I have messed around with TH settings of .070-.110 and I am getting a situation where the rifle will shoot anywhere from 3-5 shots at a set velocity with good grouping and all of the sudden it will bang out a max power shot with a lot of air use with a different POI. I can feel and hear it when it happens. Anyone have any suggestions as to what the hell is happening? By the way this is with JSB Exacts, heavies, CPL, CPH, Kodiaks, FTS thought maybe pellet resistance was causing variable backpressures buy don’t think thats the cause anymore.
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Viewing 8 replies - 1 through 8 (of 8 total)
O.T.E., With screaming pellets there is no way to tell if you are a good shot or not 😆
Because of the drag coefficient a hypersonic pellet is only hypersonic for a short distance. Then it gets beat by the sound wave making it erratic to the point of tumbling and hitting even sideways at times at a distance. But it sounds like you knew that already.
I had a steep learning curve at first tuning for maximum but as I shot a lot and the PSI and FPS dropped, my shooting proved more consistent with less noise.
After you check for the frame burrs mentioned above, or at the same time, try shaking the air tank. If something rattles, it needs tore down. Also, when low on PSI it would be a good time to bleed all the air out and manually check the valve seat return spring. You should be able to push it down and let it spring back up. if the valve return spring isn’t working with no air, there is a chance the air pressure will seat it when pressure is high enough but it may just stay open a little to long as PSI decreases.
In my experience the Power Wheel set much above 5 has an adverse effect on trigger pull that causes more erratic shots. Granted my new .25 is working set at 9, 7.5 but that is with full Talon Tunes Mods by the expert himself.
Some say anything above 950 FPS is wasted effort as the drag coefficient increases so rapidly that the velocity gained is lost in a few short yards. The BC drops drastically due to this effect. Pellet rifles and their pellets do not opperate the same as powder burner rifles with their boat tail projectiles. However, now there are Crossover air rifles with unchoked barrels pushing powder burner type bullets very accurately to greater distances than 150 yards. Every increase in performance has an increase in cost and a different notch of usefulness.
I couldn’t bare to go back to 24″ .22 from my Enlightened Hammer Quiet tuned down 12″ .177 Condor so I bought a TT AAA .25 Condor. I have the best of 2 worlds now and who knows, maybe in two years I’ll reap the bennefit of the big boys costly development of the CrossOver .257.
An issue I have that is similar is I am chasing valve lock.
With PW set at max I overcome valve lock at 1800 PSI. At that setting and pressure, 11.6 gr .177 pellets are screaming at 1240 FPS.
Ok fine, I turn the PW to 4 to slow it down. When the pressure drops to 1600 PSI, I once again overcome valve lock and they are screaming again.
Turn the PW to 2. When the pressure drops to 1400 PSI, guess what happens.
I’m thinking that after I tune my top hat (which I want to do anyway) I may need a small o-ring or something behind the top hat.
HI Killer,
If still having problems, like ssshooter said, the frame sometimes gets bad burrs. Not only along where the cocking knob sorta is supposed to latch (no matter if snug or loose, mine bounces out of latch). And mine developed Real Bad burrs at the forward end of the cocking slot. Dang, It’s only aluminum. Look at the black plastic around the ends of the hammer. Is it getting scratshes or even gouges? if so , you need to file off the burrs.You may get the old consistency back with lower preload.
After you have that taken care of, get a rubber o-ring about the size of the valve stem and put it behind the top hat. If velocity suffers to much you may have to turn the top hat adjustment out a quarter turn. Be careful, the set screws easily dent the valve stem. Not so tight but with a tiny bit of blue locktite to keep them from loosening.
The o-ring trick, described by powderburner, seems to lessen hammer bounce and reduce the amount of air used per shot, giving most guys more and more consistent shots.
But, take care of that bad burr first or you won’t see the benefit from the o-ring.
And let us know if we lied any 😆
Or may be a little more pre-load on the valve return spring. 😕
I will check on the breech side of things but it seems odd that its a random high power shot not the opposite. Most of the time its a consistent expected velocity.
I checked the TH and with the new valve with the two set screws its not going anywhere.
I am thinking maybe occasionally the valve is doing a mini dump?
should i try a different valve spring?
ended up picking up one of those nappy shot gun cleaning rods, and use it to clean the tube, (Frame), and thenusing graphite spray. Seems to help.
When the consistency goes south, (about every 2000 rounds or so, I give her a good cleaning.
Also check to make sure your to hat isn’t spinning. They must be kept tight!
Mike
Just a guess…. Is the breech sticking or facing variable friction? Some people will disassemble and put graphite spray in the tube and on the breech. Also check for burrs near the cocking knob cut outs in the frame. Good luck!
Viewing 8 replies - 1 through 8 (of 8 total)
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Sounds like your fill is too high, and the top hat is turned out way too far.
Try a 2500 psi fill, and turn the top hat in to .070″, with the power wheel set around 2 or three. (You can use feeler gages from the auto parts store to set the TH.) If you use an “O” ring behind the TH, you will have to increase this a little. But not much! 😉
Let us know what happens.