Dang that is SMOKIN' I have an AT 44 PA short in .177, them are more like the speeds I get with Xman 10.5 gr. Wonder if it would like NSA 13.4 gr slugs, most of my PCP pellet barrels love them. Also kept mine unregulated added a Long air tube, barrel extension to attach Fancy LDC past the extended tube, get 4 mags from a 2500 PSI fill, with narrow FPS spread.
Instructions for the Robt. Lane reg for the at44 say to go with twice the valve spring tension. I have the Huma reg in my .25 cal at44 and that made a difference for me.
Jere:Yeah...I’d be a bit frustrated as well. That’s fast, but that’s a whole lot of air being used and it looks a whole lot like an unregulated shot string.Not real clear to me...you’re increasing string tension as you go along?...or just leaving it alone to see what happens once it runs past reg-set?Running past reg set might at one spring tension might tell you more.
Seems to me there's too much hammer spring, and too low of a regulator setting? Just to clarify, what speed does the gun shoot currently with the regulator installed, and with what weight pellet?What speed are you wanting it to shoot?
There's also a spacer in between the hammer spring and the hammer that can be removed to decrease the tension farther.
The more I think about it, there could also be something going on with the de-bounce "wishbone" in the gun. You didn't by chance remove it did you? If so, that would definitely cause some issues. That little piece works quite well in those guns, so it could be damaged, if you didn't remove it. My first thought still stands too, of course.
Quote from: Back_Roads on May 04, 2021, 07:15:59 PM Dang that is SMOKIN' I have an AT 44 PA short in .177, them are more like the speeds I get with Xman 10.5 gr. Wonder if it would like NSA 13.4 gr slugs, most of my PCP pellet barrels love them. Also kept mine unregulated added a Long air tube, barrel extension to attach Fancy LDC past the extended tube, get 4 mags from a 2500 PSI fill, with narrow FPS spread.Great tune! If you have a string you could post for those 40 shots, that would be nice.[/quote I will have to take it out and run a string lost my old strings in a phone accident. But will do because I need new info for myself also. Was a Close out or refurb deal, did not cost me much more then a Maximus at the time, who ever refurbed it dood it good IMO, one reason I likr Field supply refurbs, never been let down.
Quote from: Rallyshark on May 04, 2021, 08:42:18 PMSeems to me there's too much hammer spring, and too low of a regulator setting? Just to clarify, what speed does the gun shoot currently with the regulator installed, and with what weight pellet?What speed are you wanting it to shoot? Current speed - 850 to 910, depending upon where the reg was set. Probably could have gone higher. I would like to be at 850 to 900 FPS. All with JSB 10.34 gr pellets.QuoteThere's also a spacer in between the hammer spring and the hammer that can be removed to decrease the tension farther.I hadn't thought of that. Thanks! But if a lighter spring seems to be necessary, would you have any suggestions as to where to find one?QuoteThe more I think about it, there could also be something going on with the de-bounce "wishbone" in the gun. You didn't by chance remove it did you? If so, that would definitely cause some issues. That little piece works quite well in those guns, so it could be damaged, if you didn't remove it. My first thought still stands too, of course. I had removed it, but bounce was terrible, so I put it back in. Thanks again!
Quote from: GoneShootn on May 04, 2021, 10:06:44 PMQuote from: Rallyshark on May 04, 2021, 08:42:18 PMSeems to me there's too much hammer spring, and too low of a regulator setting? Just to clarify, what speed does the gun shoot currently with the regulator installed, and with what weight pellet?What speed are you wanting it to shoot? Current speed - 850 to 910, depending upon where the reg was set. Probably could have gone higher. I would like to be at 850 to 900 FPS. All with JSB 10.34 gr pellets.QuoteThere's also a spacer in between the hammer spring and the hammer that can be removed to decrease the tension farther.I hadn't thought of that. Thanks! But if a lighter spring seems to be necessary, would you have any suggestions as to where to find one?QuoteThe more I think about it, there could also be something going on with the de-bounce "wishbone" in the gun. You didn't by chance remove it did you? If so, that would definitely cause some issues. That little piece works quite well in those guns, so it could be damaged, if you didn't remove it. My first thought still stands too, of course. I had removed it, but bounce was terrible, so I put it back in. Thanks again!Removing the spacer will take out a lot of hammer spring, and should give you plenty to work with. However, should you need an even lighter one, Ace hardware usually has a very good spring selection. Simply take the factory one with you to match it up with one that will fit. I believe you'll want one with an OD of 5/16 going by non metric sizing.A reg setting of 115-120 bar will give you plenty of flexibility on the speed, while still allowing you to stay in the range you want. All of that being said, something is wrong in the gun. I went back and re-read everything, and your strings shouldn't have been varying that wildly. Even with the changes you were making, something is definitely up. You have a blown o-ring somewhere in the mix I think. It could be with the probe o-ring inside the barrel, the two on either side of the barrel port, the transfer port, or even one of the ones in the valve. I saw the variation in your unregulated string too. If you swapped the whole cylinder/valve over, then that rules out anything on the valve. The only other thing that would be likely to cause that much variation in speed that isn't an o-ring would likely be related to the debounce in some way. Be it with the spring that sits on top of it, or the debounce catching the hammer when it goes by on the initial strike. Something is going on somewhere though, and the whole reg situation and thoughts on it, can be thrown out the window until you solve that velocity variation. I would double check the debounce, and make sure it doesn't have any gnarly edges and is moving properly, and check for puffs of air somewhere too. Solve that, and I think the rest will fall into place. I hope that helps
Quote from: Texpatriate on May 04, 2021, 07:29:27 PMInstructions for the Robt. Lane reg for the at44 say to go with twice the valve spring tension. I have the Huma reg in my .25 cal at44 and that made a difference for me."Valve spring tension?" - that's a new one to me.We learn new things all the time. One spring holds the valve closed and one drives the hammer to pop it open. If altering the tension of one is effective why not the other? With the reduced air pressure in the regulated valve the stock hammer spring, even at lowest setting, is too much for the stock valve spring. If a little more tension is needed shims can be used on the stock spring. In other cases the spring is replaced with a stronger one. Robt. Lane has a table showing how much various guns should be altered. It shows the at44 should be increased by a factor of 2 (twice as stiff).
Quote from: GoneShootn on May 04, 2021, 09:41:29 PMQuote from: Texpatriate on May 04, 2021, 07:29:27 PMInstructions for the Robt. Lane reg for the at44 say to go with twice the valve spring tension. I have the Huma reg in my .25 cal at44 and that made a difference for me."Valve spring tension?" - that's a new one to me.We learn new things all the time. One spring holds the valve closed and one drives the hammer to pop it open. If altering the tension of one is effective why not the other? With the reduced air pressure in the regulated valve the stock hammer spring, even at lowest setting, is too much for the stock valve spring. If a little more tension is needed shims can be used on the stock spring. In other cases the spring is replaced with a stronger one. Robt. Lane has a table showing how much various guns should be altered. It shows the at44 should be increased by a factor of 2 (twice as stiff).
If you can't get any drop of velocity when backing off the hammer spring tension, it is likely too strong for the lowered pressure supplied by the reg.... Two critical things on the Hatsan.... You must put a pin in the hole to prevent the hammer from turning.... and backing off the hammer spring means turning the adjuster clockwise when viewed from the back, the opposite of what you might think....Bob
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Personally, I would reduce the hammer spring, rather than increase the valve spring....Bob
Quote from: rsterne on May 06, 2021, 09:33:56 AMPersonally, I would reduce the hammer spring, rather than increase the valve spring....Bob It's true that you obviously know a lot more about this than I do. It's also true that it's a lot easier to fine tune the hammer spring. I know that's what most people do. I think Lane suggested both. On the other hand, with the stiffer spring in the regulated valve I can switch to an unregulated cylinder without changing my hammer spring setting.