Hatsan AT44-10 Valve Mod plus Regulator?

[LDP]

Ok here is another 20 shots on the regulator, I did tune it down a bit, I need to turn it back up for a higher fps. I think that If I converted the AT44 Tac into a long it would be a monster, I would have bought the long if they offered it over here in the states. but here is a group just to show how well the regulator works from Roy. With a AT44 long you should be able to make all the shots usable shooting JSB 18.13gr around 920fps 30shots ez with this regulator. what I like is that he is fast and local
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ES-9

Bwalton are you saying a long tactical or just a long? The at44 long is available but i did not know there was a long tactical.

[Mod90]

just over 1% es. nice

[Bwalton]

Ok here is another 20 shots on the regulator, I did tune it down a bit, I need to turn it back up for a higher fps. I think that If I converted the AT44 Tac into a long it would be a monster, I would have bought the long if they offered it over here in the states. but here is a group just to show how well the regulator works from Roy. With a AT44 long you should be able to make all the shots usable shooting JSB 18.13gr around 920fps 30shots ez with this regulator. what I like is that he is fast and local
809

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HI-813

LOW-804

AVG-808

ES-9

Bwalton are you saying a long tactical or just a long? The at44 long is available but i did not know there was a long tactical.

Yes they make a long Tactical, but they do not import them here, they also do not import all the other cool AT44's with the camo, and the wood grain with the thumb hole.... we get all the 2nd hand stuff here.
http://www.hatsan.com.tr/en_new_at44_10_tact.html


http://www.hatsan.com.tr/en_at44_10.html

[crosman999]

   The camo one is mean looking!! Glad you got the regulator,looks as though it was a smart buy and something cool to fiddle with.

[Bwalton]

Ok here is another 20 shots on the regulator, I did tune it down a bit, I need to turn it back up for a higher fps. I think that If I converted the AT44 Tac into a long it would be a monster, I would have bought the long if they offered it over here in the states. but here is a group just to show how well the regulator works from Roy. With a AT44 long you should be able to make all the shots usable shooting JSB 18.13gr around 920fps 30shots ez with this regulator. what I like is that he is fast and local
809

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HI-813

LOW-804

AVG-808

ES-9

Just got more air and did another 20 shot string... This regulator is working well The only thing that I am wondering if you can chime in Bob,  is that without a regulator I was 890fps.  Is it common to loose fps using a regulator and the air space? Would I gain all that back and then some if I used A Hatsan AT44 long seeing that it has a larger air tube and shoots 100fps more  then the AT44 short? The short has a 180cc tube and the long has a 230cc tube...
I think that this is great to tame the Hatsan with out loosing power..... Now I get 20 usable shoots from a 200bar fill.. But would like more power! Thinking about changing to the long..which I think will give me more power and more shoots. But still it may depend on the regulator set-up? what about using a 2 1/2 inch stand off?
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[rsterne]

You may have been at 890 fps at peak, but what was the gun shooting at the regulator setpoint pressure.... That is the only valid comparison....

Bob

[Bwalton]

You may have been at 890 fps at peak, but what was the gun shooting at the regulator setpoint pressure.... That is the only valid comparison....

Bob

No the 890 was without the regulator...I had it tuned without the regulator as follows:
H-883
L-870
the Es- was like 13.....if I remember right.
I just shot this 5 shot group which is even better then before. But I need to know what do I need to do to get it to shoot into the 900's with a regulator? that's what I like about Hatsan you can switch things up with no problem.
So my question is, if I go to the long air tube and barrel will the fps still remain the same with the regulator? even though the gun has increase power? does the stand off dictate the psi per shot?

[rsterne]

OK, so it wasn't 890 without the regulator, it was 870 at the low pressure end of the string, right?.... and that assumes you shot it down to whatever your regulator setpoint is....

The standoff / plenum volume and the regulator setpoint dictate the maximum fps, not the reservoir size.... The longer reservoir will just increase the number of shots... HOWEVER, increasing the barrel length will increase the velocity....

Bob

[Bwalton]

So I should increase the plenum volume which in turn will give me more psi per shot right.
this is where its at now giving me 23 shots @ a ES-of 9
"I think your spacer is about 1.71",since your tube id 1.02" instead of 1.03" that's about 22cc plus and minus regulated at 1885 should give you around 30 fpe.i don't have the tube to test the reg but the springs that I use should max out about 2000psi."

Now I would like to cut the shots down to 15 and add more plenum volume to give me a higher fps per shot..does that make sense?

[rsterne]

If your goal is 30 FPE, I would try to get a total of 30cc downstream of the regulator, including the valve volume, and make sure that the inlet of the valve is less restricted than the outlet.... Increasing all the port diameters, up to about 75% of the bore (ie 0.165" or equivalent) should allow the gun to get you the power you want without having to run too high a setpoint.....

Bob

[Bwalton]

After a week of testing the regulator has worked very well. Only a single digit ES......Now I can truly stand by Roy's (Milo74) Hatsan regulators....he has done a fine job! very simple and ez to install and adjust.

[rsterne]

It would be a good idea if you shared your setup (setpoint pressure, plenum volume, spring preload, port mods) with others here on the Forum, and the results you obtained (shot string, pellet weight, pressure drop).... It will help others considering this purchase....

Bob

[Bwalton]

Well the only mod that I have done was yours Bob in a round about way... I plug two holes and left 4 holes open...with 3 1/2 turns out on the hammer spring which gave me an avg of 890fps with a ES of 13fps...Thats without the regulator,  also keep in mind that this is with the Hatsan AT44-10 short version.
With the regulator I set it to shoot @ low 800's with a ES of only 9fps ES. As far as what the regulator is set at, all that info would have to be asked to Milo74, It was just a drop in and drill a breath hole with very little adjustment. The shot string of 20 is already posted, but I will post again. Im sure that I could get more shots but I am not in need seeing that I only hunt. this is from a 200bar fill to 150bar, So 2.5 bar per shot. or in other words.... from 2900psi to 2175.psi = 36.26psi per shot. Bob will go over the math im sure
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[rsterne]

Assuming that is with 18.1 gr. JSBs, 808 fps avg. is 26.2 FPE x 20 shots = 525 FPE total....

With a 2.5" spacer, plus the regulator, you probably have an air capacity of about 8 CI.... with a 50 bar drop in pressure that is 8 x 50 = 400 CI total air used....

That would give an efficiency of 525 / 400 = 1.31 FPE/CI which is great !!!

Bob

[Motorhead]

At that power, 36.2 psi per shot is still pretty thirsty.
Losing some hammer weight ( A lot actually ) would offer IMO a huge improvement in the efficiency.

[rsterne]

1.31 x huge improvement would be spectacular !!!

Bob

[Bwalton]

At that power, 36.2 psi per shot is still pretty thirsty.
Losing some hammer weight ( A lot actually ) would offer IMO a huge improvement in the efficiency.

yeah Scott I thought about the hammer mod, but I just dont feel like diving into that as of yet, maybe latter I still have yet to deal with the BT65. but from what I am finding out I should be able to tune the BT65 in a few hours, holes plug, barrel re- crowned, and go from there. I am going to order another AT44 in long .22 and covert the Tact to a long and that would be a true mini hammer
and have the other one as a short to lend to friends that want to try out the darkside or may just have a .177

[Bwalton]

testing the spread sheet