Author Topic: Hatsan AT44-10 Valve Mod plus Regulator? (Read 14051 times))

Bwalton · « **on:** June 20, 2014, 12:11:26 PM »

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

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.

rsterne · « **Reply #1 on:** June 20, 2014, 12:27:49 PM »

How much plenum volume are you running between the regulator and the valve?.... and what is the regulator setpoint?....

Bob

Bwalton · « **Reply #2 on:** June 20, 2014, 12:35:43 PM »

Quote from: rsterne on June 20, 2014, 12:27:49 PM

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

rsterne · « **Reply #3 on:** June 20, 2014, 12:44:16 PM »

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

Bwalton · « **Reply #4 on:** June 20, 2014, 12:47:36 PM »

Quote from: rsterne on June 20, 2014, 12:44:16 PM

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?

milo74 · « **Reply #5 on:** June 20, 2014, 12:58:36 PM »

Quote from: Bwalton on June 20, 2014, 12:35:43 PM

Quote from: rsterne on June 20, 2014, 12:27:49 PM
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.

Bwalton · « **Reply #6 on:** June 20, 2014, 01:14:47 PM »

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!

Bwalton · « **Reply #7 on:** June 20, 2014, 01:53:36 PM »

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!

rsterne · « **Reply #8 on:** June 20, 2014, 02:03:59 PM »

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

Bwalton · « **Reply #9 on:** June 20, 2014, 02:13:24 PM »

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.

Bwalton · « **Reply #10 on:** June 20, 2014, 03:16:00 PM »

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?

Motorhead · « **Reply #11 on:** June 20, 2014, 04:22:23 PM »

Opening up the poppets seats I.D. hole slightly sure helped my AT-44 produce a tad more power once regulated.

Bwalton · « **Reply #12 on:** June 20, 2014, 04:50:25 PM »

Quote from: Motorhead on June 20, 2014, 04:22:23 PM

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?

Motorhead · « **Reply #13 on:** June 20, 2014, 05:24:25 PM »

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

Check with Bob ( Rsterne ) and see what he can offer in pictures being most shared in previous threads were his

Scott

rsterne · « **Reply #14 on:** June 20, 2014, 05:41:12 PM »

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

Bwalton · « **Reply #15 on:** June 20, 2014, 05:49:17 PM »

Quote from: rsterne on June 20, 2014, 05:41:12 PM

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

Bwalton · « **Reply #16 on:** June 20, 2014, 06:14:00 PM »

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

rsterne · « **Reply #17 on:** June 21, 2014, 01:50:30 AM »

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

Bwalton · « **Reply #18 on:** June 23, 2014, 08:12:17 PM »

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

805

811

808

809

806

810

807

807

804

807

811

810

812

809

813

812

813

808

807

HI-813

LOW-804

AVG-808

ES-9

rsterne · « **Reply #19 on:** June 23, 2014, 08:29:39 PM »

Nothing wrong with an ES of 9 in a regulated gun....

Bob

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Hatsan AT44-10 Valve Mod plus Regulator?

Author Topic: Hatsan AT44-10 Valve Mod plus Regulator? (Read 14051 times))