GTA
All Springer/NP/PCP Air Gun Discussion General => PCP/CO2/HPA Air Gun Gates "The Darkside" => Topic started by: Bwalton on June 20, 2014, 12:11:26 PM
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I am still playing around with the Hatsan seeing how well can I improve it with the least amount of work. So far a recap. I did a re-crown (free), and the Valve mod that Bob shared with us all (the cost of two set screws)...... Roy has been so kind as too design a regulator for the Hatsan AT44-10.
So I have been working with him on this to get it right so that he can share it with the airgun community.
Yesterday put a smile on my face ;D because the numbers were awesome! The first test I did a 11 shot group with the High of 859fps and the low of 844fps thats a 5fps spread! This was using JSB 18.13gr
I would like to see the fps around 900... but if I cant get it there I can drop down to the JSB 15.89gr
If this was the AT4410 long then 900 would not be a problem, but the short is not as powerful as the long. Once this is worked out I'm hoping that he will make one for the BT65. He also makes them for the M-rod and I think that he has a blog on here about that. I will post a video of the chrono and regulator in action.
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How much plenum volume are you running between the regulator and the valve?.... and what is the regulator setpoint?....
Bob
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How much plenum volume are you running between the regulator and the valve?.... and what is the regulator setpoint?....
Bob
Bob I have absolutely no idea, Roy would have to chime in seeing that he designed it...the spacer I know is 2-2 1/2 inches , I know that I tuned the regulator out cc about 1 1/2 turns
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The Hatsan tube is about 1" ID, so assuming a thin wall tube spacer with a 7/8" ID and 2" of length that would be about 20cc, and 2.5" would be 25cc, so you should be fine.... You should only need about 100 psi higher pressure with the regulator than without (at the low pressure end of the shot string) to get the same velocity....
Bob
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The Hatsan tube is about 1" ID, so assuming a thin wall tube spacer with a 7/8" ID and 2" of length that would be about 20cc, and 2.5" would be 25cc, so you should be fine.... You should only need about 100 psi higher pressure with the regulator than without (at the low pressure end of the shot string) to get the same velocity....
Bob
Thanks Bob! Now would I gain shots or loose a few shots? or would it all balance out because of the regulated air?
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How much plenum volume are you running between the regulator and the valve?.... and what is the regulator setpoint?....
Bob
Bob I have absolutely no idea, Roy would have to chime in seeing that he designed it...the spacer I know is 2-2 1/2 inches , I know that I tuned the regulator out cc about 1 1/2 turns
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.
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So the 2000psi will give me down to 137bar, all I need is 15shots when I hunt. last time I went I did not waste very many shots, actually out of the four GS that I took one at 77yards, one at 73yards,and one at 40yards all one shot each, the only one that I took two shots on was a juvenile that was too close and did not know the hold..
This will be an awesome addition to the AT4410's!
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today I will do a 20 shot string but only need 15shots for hunting, if it keeps the fps spread 25 and under I will consider this regulator to Hatsan what oak is to a BBQ......brings out all the great taste!
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I don't know what kind of spacer is used, if it is a small rod that doesn't displace volume then the plenum will be larger for a given length.... In any case, 22cc is large enough, even for a 30 FPE gun, although the setpoint will have to be slightly higher than the same pressure will produce in an unregulated gun....
Most regulators I have worked with will hold about a 1% ES or a bit more (10-13 fps over the entire string) and that with unsorted JSB pellets.... If your ES is up around 2% I would suspect the regulator isn't quite as stable as I would like to see....
Bob
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right now it holds a high of 859fps and a low of 854fps so a Es of 5fps...........thats on a 11 shot string, my Hatsan is good for a 20 shot string before it starts to dip downward, So to keep a es of 5fps over a 20 shot string would be great. The accuracy is already overwhelming.
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my needs are as follows: I need 15ftlbs@ 70 yards.. so I need a 31.88ftlb set-up which is the same as shooting the JSB 18.13gr @ 890fps. right now I'm at 857fps avg.... So I need to find 33fps, which im sure Its in there some where.. just have to look for it. maybe a little longer spacer?
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Opening up the poppets seats I.D. hole slightly sure helped my AT-44 produce a tad more power once regulated.
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Opening up the poppets seats I.D. hole slightly sure helped my AT-44 produce a tad more power once regulated.
Thanks Scott but a guy like me would need a little more direction, you have pics on a blog here some where?
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There are a few shots here within the GTA of what the dismantled AT-44 valve looks like.
Seat in question is a Nylon type material that has an o-ring around it and simply press's into the body cavity.
When i did mine carefully held seat in my "Mini lathe" and using a VERY sharp drill slowly drilled the I.D. out to within @ .030" of the poppets head diameter.
Sadly never documented it and being I no longer own my Regged AT-44 have no way to revisit and get any further data for you :P
Check with Bob ( Rsterne ) and see what he can offer in pictures being most shared in previous threads were his ;)
Scott
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I found your extra FPE at 70 yards for you.... The BC of those 18 gr. JSBs is 0.036, which with a muzzle velocity of 850 fps (29 FPE) leaves you 18 FPE remaining at 70 yards and nearly 15 FPE at 100 yards....
You should be able to get a 1% ES (or very close) over the entire pressure range.... If you are filling to 200 bar and the setpoint is 130 bar, that is 70 bar of headroom on a reservoir of about 150 cc (180 - regulator - plenum).... That gives you about 640 CI of air, which at 1 FPE/CI would be 640 FPE, and at 29 FPE per shot that should be 22 shots.... If you're not getting at least 20 shots from a 200 bar fill your efficiency is below what I would expect....
BTW, you said a high of 859 and a low of 844, which is a 15 fps spread, not 5.... I guess the 844 was wrong....
Bob
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I found your extra FPE at 70 yards for you.... The BC of those 18 gr. JSBs is 0.036, which with a muzzle velocity of 850 fps (29 FPE) leaves you 18 FPE remaining at 70 yards and nearly 15 FPE at 100 yards....
You should be able to get a 1% ES (or very close) over the entire pressure range.... If you are filling to 200 bar and the setpoint is 130 bar, that is 70 bar of headroom on a reservoir of about 150 cc (180 - regulator - plenum).... That gives you about 640 CI of air, which at 1 FPE/CI would be 640 FPE, and at 29 FPE per shot that should be 22 shots.... If you're not getting at least 20 shots from a 200 bar fill your efficiency is below what I would expect....
BTW, you said a high of 859 and a low of 844, which is a 15 fps spread, not 5.... I guess the 844 was wrong....
Bob
Yes im sorry its 854 not 844, Bob thats gives me a whole lot better look as I had the BC set up in chairgun @ .0330
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Am I missing something? shooting @ 850fps with the JSB 18.13gr BC .0360 im getting 14.57ftlb @ 70yards and 10.84 @100yards
Now shooting@ 950fps would give me those numbers, but not 850fps
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ChairGun Pro (v4.1.6) I get 18.1 gr @ 850 fps = 29.03 FPE, with 669.6 fps (18.01 FPE) at 70 yards and 608 fps (14.85 FPE) at 100 yards.... using a BC= 0.036, profile GA....
Bob
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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 ;D
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ES-9
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Nothing wrong with an ES of 9 in a regulated gun....
Bob
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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 ;D
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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.
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just over 1% es. nice
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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 ;D
809
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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.
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_new_at44_10_tact.html)
http://www.hatsan.com.tr/en_at44_10.html (http://www.hatsan.com.tr/en_at44_10.html)
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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. 8)
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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 ;D
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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 ;D 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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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
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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?
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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
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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?
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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
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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.
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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
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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 ;D
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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
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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.
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1.31 x huge improvement would be spectacular !!!
Bob
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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 ;D
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
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testing the spread sheet ;D