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All Springer/NP/PCP Air Gun Discussion General => PCP/CO2/HPA Air Gun Gates "The Darkside" => Topic started by: GoneShootn on May 03, 2021, 10:02:07 PM

Title: AT44 + reg = stumped!
Post by: GoneShootn on May 03, 2021, 10:02:07 PM
It's been a long time since I fooled around with my Hatsan AT44 .177, so I got it out the other day and decided to finally tune it with the new Audrius reg in. I had seen Bob Sterne's scholarly treatise on the subject and then watched the Brothers in Air YT video as a refresher. The idea was to increase the hammer spring to the FPS plateau and then back off a bit. If final velocity is not where I want it, then adjust the reg and repeat. Worked like a charm with my Marauder .25 which is now stacking pellets at 35 yds. Velocity only at about 815 FPS, but I can live with 37 FPE and pellets going where I aim.

So on to the AT44. Same procedure, only adjusting the HS has no effect at all. I have tried reg settings to give strings of around 825 FPS and then one to give around 900 FPS plus one in between, all at HS=0. Each time, however, when I advanced the HS outward, or upward, there was little, if any, change. I'm thinking maybe the valve spring is broke,, but I checked and it isn't. Another thing that is happening, which may be unrelated, is that every 5 shots or so I get one that is 70 FPS lower than the average of the others.

As I said, it's been a while since I've been down this road, so I may have forgotten something important. Strike that. I have probably forgotten something important. Any suggestions will be appreciated.
Title: Re: AT44 + reg = stumped!
Post by: Back_Roads on May 03, 2021, 10:34:49 PM
 Might be something like a breach oring going bad, or hammer drag, etc, best to dig into it may be simple, may take all of our brains  :-\
Title: Re: AT44 + reg = stumped!
Post by: GoneShootn on May 03, 2021, 10:47:09 PM
Might be something like a breach oring going bad, or hammer drag, etc, best to dig into it may be simple, may take all of our brains  :-\

I guess I'm going to have to put on my mechanic's hat and roll my sleeves up. We'll see what we see. :)

Thanks.
Title: Re: AT44 + reg = stumped!
Post by: elguapo99 on May 03, 2021, 11:50:48 PM
You may already know this but when adjusting the hammer spring, make sure that the hammer is not rotating by inserting a punch in the hole to keep the hammer from turning. The hammer spring will not adjust if the entire mechanism turns.
Here's an explanation by rsterne: http://www.canadianairguns.com/showthread.php?656-Hatsan-25-cal-AT44S-10-Long-Mods (http://www.canadianairguns.com/showthread.php?656-Hatsan-25-cal-AT44S-10-Long-Mods)
Title: Re: AT44 + reg = stumped!
Post by: Pelletjunkie on May 04, 2021, 12:48:48 PM
I’m not a Hatsan guy so I don’t know if the At44 came from the factory with a reg. If it didn’t, you have some porting to do.
Title: Re: AT44 + reg = stumped!
Post by: GoneShootn on May 04, 2021, 01:44:43 PM
You may already know this but when adjusting the hammer spring, make sure that the hammer is not rotating by inserting a punch in the hole to keep the hammer from turning. The hammer spring will not adjust if the entire mechanism turns.
Here's an explanation by rsterne: http://www.canadianairguns.com/showthread.php?656-Hatsan-25-cal-AT44S-10-Long-Mods (http://www.canadianairguns.com/showthread.php?656-Hatsan-25-cal-AT44S-10-Long-Mods)

Good suggestion. Doesn't seem to be the problem. I have drilled a hole to allow external access. Wish it was. Thanks.
Title: Re: AT44 + reg = stumped!
Post by: GoneShootn on May 04, 2021, 01:46:48 PM
I’m not a Hatsan guy so I don’t know if the At44 came from the factory with a reg. If it didn’t, you have some porting to do.

It didn't. Anyway, I wouldn't think that adding a reg would make the HS adjustment totally useless, but what do I know? ;)
Title: Re: AT44 + reg = stumped!
Post by: Tucobenedicto on May 04, 2021, 02:20:25 PM
If you don't see a speed drop even at the minimum hammer spring preload, maybe is time to switch to a softer hammer spring or cut some coil from the spring. Can happen if the regulated pressure is considerably lower respect to the original fill pressure.
Title: Re: AT44 + reg = stumped!
Post by: Ribbonstone on May 04, 2021, 02:20:44 PM
Just a couple of questions….not having used that regulator...and stuff you already know.

But sometimes we get kind of narrow focused.

Assuming there is no mechanical problem and everything is working normally.

1. Does it reduce velocity if you back the spring tension way off.  Would not make for the speed you want, but if it then acts like you’d expect a regulator to act, at least know it works. 

By testing, could get a ball park idea of what the real world output pressure.

2. Plenum size?

I expect that at a certain point, more spring tension doesn’t give significant velocity change...basically ran out of pre-regulated air.  May not be able to easily change the plenum.
Title: Re: AT44 + reg = stumped!
Post by: GoneShootn on May 04, 2021, 02:27:22 PM
If you don't see a speed drop even at the minimum hammer spring preload, maybe is time to switch to a softer hammer spring or cut some coil from the spring. Can happen if the regulated pressure is considerably lower respect to the original fill pressure.

Makes a lot of sense. Thanks.
Title: Re: AT44 + reg = stumped!
Post by: GoneShootn on May 04, 2021, 02:31:08 PM
Just a couple of questions….not having used that regulator...and stuff you already know.

But sometimes we get kind of narrow focused.

Assuming there is no mechanical problem and everything is working normally.

1. Does it reduce velocity if you back the spring tension way off.  Would not make for the speed you want, but if it then acts like you’d expect a regulator to act, at least know it works. 

By testing, could get a ball park idea of what the real world output pressure.

2. Plenum size?

I expect that at a certain point, more spring tension doesn’t give significant velocity change...basically ran out of pre-regulated air.  May not be able to easily change the plenum.

Will have to shoot it down to get idea of true reg pressure, but I'm guessing now sitting at 100 to 110 bar. And will have to look up the reg specs. So I'll have to get back to you. Thanks.
Title: Re: AT44 + reg = stumped!
Post by: GoneShootn on May 04, 2021, 03:32:39 PM
Installed the 2nd, unregulated, cylinder and filled to 200 bar. This thing is a beast! I had forgotten how gnarly it was. With all 6 ports open and HS at 0 (assuming mechanically ok), FPS is well over 1000 with JSB 13.43gr pellets. With 3 holes plugged, it is still over 1000 FPS. Going down to 1 hole.
Title: Re: AT44 + reg = stumped!
Post by: GoneShootn on May 04, 2021, 05:13:20 PM
Result with 1 valve hole open below. I'm going to dig out the old unreged tuning info and see what that looks like.

Filled to 170 bar
HS increased from 0 to 5 over string
Finished at 130 bar
1 valve hole open
JSB 13.43 gr pellets

Shot count: 14
Low: 817
Hi: 909
Avg: 881
STD Dev: 27.1
Spread: 92.0

5/4/21 3:39:47 PM,907
5/4/21 3:39:55 PM,907
5/4/21 3:40:52 PM,835
5/4/21 3:41:00 PM,909
5/4/21 3:41:08 PM,905
5/4/21 3:42:05 PM,902
5/4/21 3:42:12 PM,898
5/4/21 3:42:17 PM,884
5/4/21 3:42:25 PM,884
5/4/21 3:43:22 PM,817
5/4/21 3:43:54 PM,879
5/4/21 3:44:00 PM,872
5/4/21 3:44:06 PM,868
5/4/21 3:44:13 PM,863
Title: Re: AT44 + reg = stumped!
Post by: Privateer on May 04, 2021, 06:13:01 PM
Never cared for the Hatsan .177's
Out of the box they all seemed to shoot hot.
Opening ports just compounds that issue.
Title: Re: AT44 + reg = stumped!
Post by: GoneShootn on May 04, 2021, 07:06:31 PM
Never cared for the Hatsan .177's
Out of the box they all seemed to shoot hot.
Opening ports just compounds that issue.

Not exactly. They come with all 6 ports open, and they are HOT, so 2 things you can do: close off some of the ports and/or (I assume) get a weaker hammer spring. I think this will be a shooter if I can get it right.
Title: Re: AT44 + reg = stumped!
Post by: 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.  :o 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.
Title: Re: AT44 + reg = stumped!
Post by: Texpatriate on May 04, 2021, 07:29:27 PM
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.
Title: Re: AT44 + reg = stumped!
Post by: Ribbonstone on May 04, 2021, 07:50:00 PM
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.
Title: Re: AT44 + reg = stumped!
Post by: Rallyshark on May 04, 2021, 08:42:18 PM
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.  Of course, on a AT-44 CW decreases HS/speed and CCW increases HS/speed, but I'm sure you already knew that. 

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. 
Title: Re: AT44 + reg = stumped!
Post by: Back_Roads on May 04, 2021, 08:57:03 PM
 Something I have not heard of breaking recently is that wishbone debounce device ??? >>>  :-\
Title: Re: AT44 + reg = stumped!
Post by: GoneShootn on May 04, 2021, 09:38:35 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.  :o 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.
Title: Re: AT44 + reg = stumped!
Post by: GoneShootn on May 04, 2021, 09:41:29 PM
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.

"Valve spring tension?" - that's a new one to me.
Title: Re: AT44 + reg = stumped!
Post by: GoneShootn on May 04, 2021, 09:46:10 PM
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.

Sorry. It was the unreg'd cylinder, and yes, I was increasing the hammer spring tension as I shot. First one was at 0.
Title: Re: AT44 + reg = stumped!
Post by: GoneShootn on May 04, 2021, 10:06:44 PM
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?

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.

Quote
There'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?

Quote
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.

I had removed it, but bounce was terrible, so I put it back in.

Thanks again!
Title: Re: AT44 + reg = stumped!
Post by: Back_Roads on May 04, 2021, 10:28:53 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.  :o 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.
Title: Re: AT44 + reg = stumped!
Post by: Rallyshark on May 05, 2021, 12:58:03 AM
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?

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.

Quote
There'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?

Quote
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.

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 :)
Title: Re: AT44 + reg = stumped!
Post by: GoneShootn on May 05, 2021, 01:44:53 PM
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?

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.

Quote
There'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?

Quote
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.

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 :)

Thanks, Donny and everyone else. When I started this, I didn't expect a problem. Since I'm probably not going to sell the .177 (you know, SHTF and all :)), with apologies to all, I think I am going to move on to the AT44 Long in .25, which I probably will sell. I'm thinking of pulling the reg from the .177, upping the pressure a bit, which will only be a guess, and installing in the .25. Either I ordered the same reg as for the .22 (maybe for a .25) in order to get the larger plenum, or they are all the same. Don't know which. If I encounter any perplexing problems there, then I will create a new thread for that. Then I will come back to the .177 at a later date.
Title: Re: AT44 + reg = stumped!
Post by: GoneShootn on May 05, 2021, 01:53:40 PM
As I said, I'm probably not going to sell the .177 AT44, as I think it may be the ideal SHTF airgun. Pellets are cheap. You can shoot it low and slow for stealth and to get a lot of shots, and then you can generate a lot of power when you want by going to even heavier pellets and letting out the beast. It has a built-in hammer debounce device to address what is always an issue with the lower cost pcp guns, and you can easily remove it if you want. You can comfortably pump it and get a lot of shots, plus it's easy to work on. All in all, the AT44 is an impressive bit of engineering, IMHO, something important that this episode has reminded me.
Title: Re: AT44 + reg = stumped!
Post by: rsterne on May 05, 2021, 06:00:06 PM
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
Title: Re: AT44 + reg = stumped!
Post by: Texpatriate on May 05, 2021, 06:22:02 PM
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.

"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).
Title: Re: AT44 + reg = stumped!
Post by: Ribbonstone on May 05, 2021, 08:04:15 PM
Hillbilly guide to regulation:

Counter intuitive….but when running past reg setting…ignore that it was regulated up to that set point.

Once the regulator quits regulating, it’s a tiny volume non-regulated PCP and follows the same basic rules as any non-regulated PCP.

So lets pretend the reg is set for 1500psi, and you start looking hard at the shots starting from that point in the same terms as a non-regulated PCP.

As if he magic elves that were refilling your shooting chamber (plenum) went on strike and you have to consider the regulated PCP as a really tiny air volume non-regulated PCP.

So...once you are off reg….one of two things will happen (with a 3rd in a distance 3rd place).


1. Once past reg set, will drop in velocity like a narcoleptic buzzard.  The “Korean Cliff” whetre it suddenly starts dropping speed with ever shot you take.  That;s a real good indication that you are hitting the valve stem too hard for best efficiency (using more air than you are getting energy out….the right hand side of Bob’s “knee graph.

2. If the velocity/energy output stays real close for several shotys after going off reg, then you are close to even.  Are getting a kind of optimum efficiency, like being in the “plateau” of a non-regulated PCP.

DISTANT 3rd place.

3. It is possible to have the velocity increase for one or two shots after the reg has stopped being a regulator.  Locked open, do have a passageway to the rest of the air tube’s volume without the time/dwell delay of the reg cycling.

WHY YOU MAY NOT CARE:

If using a tank or compressor,  or both,  efficiency is just hooking up sooner to refill.  Basically a few cents more or less of electricity for a compressor….or a little sooner trip to the fill station to refill a tank.
Title: Re: AT44 + reg = stumped!
Post by: GoneShootn on May 05, 2021, 11:13:46 PM
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.

"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).

I understand the valve spring, but in your first post it sounded like you were saying to set the reg at a pressure of 2x the valve spring, and that's what I didn't understand. But now it seems that you meant to double the valve spring strength, so how would I do that? How would I know what spring would be double the stock one? And thanks for the great info!
Title: Re: AT44 + reg = stumped!
Post by: GoneShootn on May 05, 2021, 11:22:05 PM
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

Got it. Thanks, Bob. But I started at HS=0, so it was that I wasn't seeing an increase in velocity as I adjusted it outward, or upward, or CCW.

So to begin to address the issue, I can remove the hammer spring spacer, as Donny (Rallyshark) said and/or either decrease the hammer spring strength or increase the valve spring strength. Am I understanding correctly?
Title: Re: AT44 + reg = stumped!
Post by: GoneShootn on May 05, 2021, 11:24:05 PM
One thing is for sure - I came to the right place! I am continually amazed by the depth of experience and knowledge, as well as courtesy and dedication to the sport, of the members here. Thanks for being willing to help.
Title: Re: AT44 + reg = stumped!
Post by: Texpatriate on May 06, 2021, 08:14:14 AM
[[/quote]

"Valve spring tension?" - that's a new one to me.

How would I know what spring would be double the stock one? And thanks for the great info![/quote]

That's a good question. Without the proper instruments I had to get an assortment of springs and try a couple out. It's unlikely that I got very close to exactly a factor of 2 but close enough to make a difference. For what it's worth, the spring in the newer "H class" valve feels at least twice as heavy as the old version.
Title: Re: AT44 + reg = stumped!
Post by: rsterne on May 06, 2021, 09:33:56 AM
Personally, I would reduce the hammer spring, rather than increase the valve spring....

Bob
Title: Re: AT44 + reg = stumped!
Post by: GoneShootn on May 06, 2021, 01:49:45 PM
So I will try removing the spacer first and see what that does, as BigTinBoat did in tuning his .177.
Title: Re: AT44 + reg = stumped!
Post by: GoneShootn on May 06, 2021, 01:53:06 PM
[

"Valve spring tension?" - that's a new one to me.

How would I know what spring would be double the stock one? And thanks for the great info![/quote]

That's a good question. Without the proper instruments I had to get an assortment of springs and try a couple out. It's unlikely that I got very close to exactly a factor of 2 but close enough to make a difference. For what it's worth, the spring in the newer "H class" valve feels at least twice as heavy as the old version.
[/quote]

Thanks. "H Class?" Still in the AT44 valve type? Which Hatsan part list would I go to?
Title: Re: AT44 + reg = stumped!
Post by: Texpatriate on May 06, 2021, 03:26:19 PM
Personally, 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.
Title: Re: AT44 + reg = stumped!
Post by: GoneShootn on May 06, 2021, 06:42:30 PM
Personally, 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.

More good things to know and remember! Thanks. I am certainly being schooled by good teachers, and I just hope I can pass the final exam. :) I am going to print this entire thread out.
Title: Re: AT44 + reg = stumped!
Post by: Texpatriate on May 06, 2021, 06:51:24 PM
I don't claim to have all the answers by any means. However here is some advice from someone who has most of them.
https://laneregulators.com/manuals
Title: Re: AT44 + reg = stumped!
Post by: Texpatriate on May 06, 2021, 07:21:28 PM
Thanks. "H Class?" Still in the AT44 valve type? Which Hatsan part list would I go to?

I'm not suggesting you try to get one, just pointing it out. The newer version, the "H class" is distinguished by a screwed in plug in the valve as opposed to the original white plastic plug which presses in and is pried out. Also by an H printed on the tube. I'm not sure when they made the change or even what exactly the difference is but it's a whole other thing. I put an H class cylinder in my older model gun and got about 100 fps. When I asked at Hatsan USA what was different they told me how to tell which was which. What I want to know is what makes it not work in my gun. Apart from the spring and the plug they are visually identical. I put the old school spring in the new valve and the improvement was negligible.
I did this: https://www.amazon.com/gp/product/B008RG8LXW/ref=ppx_yo_dt_b_asin_title_o05_s00?ie=UTF8&psc=1 (https://www.amazon.com/gp/product/B008RG8LXW/ref=ppx_yo_dt_b_asin_title_o05_s00?ie=UTF8&psc=1)
It wasn't till later that I remembered about the H class spring.
For all I know you may have the H class. All the principals would be the same. You would just need a really stiff spring.
Title: Re: AT44 + reg = stumped!
Post by: Texpatriate on May 07, 2021, 05:14:21 PM
Getting back to the original post. I just don't see how adjusting the HS could have no effect whatsoever unless the tool you are sticking through that hole is not actually engaging the hammer. Can you turn it  until it makes a full stop in either direction? That hole in the hammer is not likely to be directly beneath the hole in your stock. You may have to rotate the whole thing till it lines up. I can't help thinking it's that simple and we're just over thinking it.
Title: Re: AT44 + reg = stumped!
Post by: GoneShootn on May 08, 2021, 08:30:27 PM
Getting back to the original post. I just don't see how adjusting the HS could have no effect whatsoever unless the tool you are sticking through that hole is not actually engaging the hammer. Can you turn it  until it makes a full stop in either direction? That hole in the hammer is not likely to be directly beneath the hole in your stock. You may have to rotate the whole thing till it lines up. I can't help thinking it's that simple and we're just over thinking it.

Certainly a reasonable question, but I'm sure it is turning properly. Still, as you say, it doesn't make sense. I know that I can reach a stop on the loosening side, but I'll be sure I can max it out, too. If I notice anything there, I will post it here. I think, however, that the probability is that, for the reg setting the HS is already maxed out at 0, so further tightening results in no increase in FPS and maybe even a bit of decrease. Hard to tell, though, so when I can get back to it, I will remove the HS spacer, and that may tell the story.
Title: Re: AT44 + reg = stumped!
Post by: rsterne on May 08, 2021, 10:30:52 PM
If the gun is shooting on the "plateau" with the minimum HS preload at the regulated pressure, then increasing the preload will only give more dwell, and use more air (and make more noise).... If the valve is open until the pellet leaves the muzzle, no amount of extra HS will increase the velocity further.... The HS on a Hatsan is designed to create a bell-curve starting at 200 bar, peaking at maybe 140-150 bar, and then after that the velocity will drop as the pressure drops.... By definition, if your regulator setpoint is toward what is the lower end of the bell-curve pressure, you are operating on the "plateau" at that pressure, and would expect that increasing the HS preload would not add any velocity....

Bob
Title: Re: AT44 + reg = stumped!
Post by: GoneShootn on May 09, 2021, 09:54:55 AM
If the gun is shooting on the "plateau" with the minimum HS preload at the regulated pressure, then increasing the preload will only give more dwell, and use more air (and make more noise).... If the valve is open until the pellet leaves the muzzle, no amount of extra HS will increase the velocity further.... The HS on a Hatsan is designed to create a bell-curve starting at 200 bar, peaking at maybe 140-150 bar, and then after that the velocity will drop as the pressure drops.... By definition, if your regulator setpoint is toward what is the lower end of the bell-curve pressure, you are operating on the "plateau" at that pressure, and would expect that increasing the HS preload would not add any velocity....

Bob

Thanks, Bob and to all the rest, as well! I think we now know, or at least strongly suspect, the identity of the fly in the ointment, so it is now my job to work to evict the little booger. I am looking forward to that, although I may not get to it for a while.

I'm thinking about jerking the reg from the .177, which I am inclined to keep and installing it into a .25 AT44 Long that is redundant and will probably sell. The reg would make things so much easier for a potential buyer. I don't know if Audrius has more than one plenum size. I've asked once and will not ask again, but if there are more than one size, then I'm pretty sure that I ordered the .25 size for both the .22 and the .177.