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PostPosted: Tue Oct 27, 2015 3:32 am 
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I decided to start a new thread for the actual tests on the project.

ADDING A “SAIL” MOD. TO A .22 CAL. HATSAN AT44 THAT ALREADY HAS A 5 SCREW MOD.

The objective of this modification is to try to obtain about 50 good shots in the 750 to 800 fps range using a 14 to 16 gr. pellet.

This is a used Hatan AT44-10 in .22 cal. When I received it, I found that it had been modified so the power adjuster could be adjusted without taking the stock off. I also found that the valve had been modified. Five of six air holes in valve have been plugged with grub screws and the single remaining hole appears to have been slightly enlarged and flared. This remaining hole appears to have been enlarged to about .149” to .152”. There is a small air leak from the tube that allows about 100/200 psi of air to leak out over a 24 hour period. The forward O-ring on the valve has some small cuts on the outer edge where it apparently was nicked while screwing the air tube in and out of the rifle. It is not known if this is the cause of the slow air leak from the tube. Hatsan states the original rifle shoots at about 970 fps with lead pellets (I don’t think they state the weight of the pellet that gets them the 970 fps on the stock rifle.).

This modified rifle I tested was charged to 200 bar and shot down to 100 bar with the power adjuster set at two turns out. The day was sunny and warm (78 F) with no wind. Chronograph used was an Alpha Mater Shooting Chrony. 50 pellets were fired, with a low of 740 fps. and a high of 880 fps, using Crosman 14.3 Premiers. First 10 shots started at 740 and ended at 790. Next ten shots started at 781 and ended at 829. Next 30 shots started at 842 and ended at 838 with a low of 838 and a high of 880. I’m hoping some tuning will flatten this out a lot more. I think the the high of only 880 fps (vs the advertised 970 fps) is the result of the 5 screw mod, having the power adjuster at only two turns out, or the possibility that Hatsan used a much lighter pellet to arrive at the 970 fps). Maybe a combination of all three. I did this initial test as a base to see what effect the sails would have on future tests.

Tube was removed, degassed and a .375” diameter “sail” that was about .50” thick was added. The .375 inch diameter would be close to 0.025” smaller than the diameter of the valve. For testing, the tube was only filled to about 150 bar (since that was the general pressure range where the maximum FPS seemed to be) and two rounds were fired. Both rounds sounded very week and registered at only 175 fps! The .375” Sail is apparently much too large for this configuration.

I think my next sail will be made to a diameter of about .350” which would be about .050” smaller than the diameter of the valve. If anyone thinks I should go down even smaller for my next sail, please let me know. If someone thinks I should try to increase the hammer spring tension a few turns also, or any other suggestions, let me know.

If trying various sail sizes does not get me the results I want, I will try playing with a non-pal stem that has been turned down some.


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PostPosted: Tue Oct 27, 2015 11:15 am 
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A little bit can make a huge difference. Keep us posted.

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PostPosted: Tue Oct 27, 2015 12:27 pm 
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Just wanted to let you know about my results, too. I ran shots over the chrony on the weekend, and found that when topped off to 150 bar, I started shooting at 780 fps. It didn't hit it's sweet spot until about 145 bar, and then I got 40 shots from 817 - 847 fps, down to 90 bar. It started dropping under 800 fps pretty quickly after that. This is all assuming that my pressure gauge is accurate, but it seemed to reflect what was shown on my pump. This was using JSB Jumbo Heavy 18.1 gr pellets. I highly recommend trying those pellets, the guns just seem to love them.

I also find that as I shoot my string, my POI tends to drift from right to left. The difference is only about 1/2" at 50 yards, and I'm just used to compensating now.

Still, quite amazing for a relatively cheap PCP. I knocked down a Gamo Squirrel at 47 yards on first try, and shot a spoon right off the hanger bar at 53 yards. I was making a ragged hole at 25 yards with it, too. Shooting a little 5/8" paster at 25 yards, and the shots just kept pulling it in into the hole until the paster pretty much went right through!

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FX Streamline .22 - Optisan Mamba Lite 4-16X44
Hammerli Pneuma Elite 10 .22 - Bushnell Elite 4200 4-12X40
Custom Crosman 2240 w/ LW barrel - Vortex Strikefire
Remington AirMaster 77 PAL rated - CenterPoint 3-9X40


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PostPosted: Tue Oct 27, 2015 1:19 pm 
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Thanks Daryl and Barfman, It's good to know that a small difference in the diameter of the sail can have a large effect on the results. I may try a .360 sail first, then I'll still be able to trim that one down if it is still too large. It really did surprise me that the .375" sail (< .025" of the valve diameter) reduced the speed from the high 800 fps to as little as 175 fps.. I guess my next test will tell me just how much a difference decreasing the sail by another .015" will make. .015" just doesn't sound like a lot but I guess we'll see.

Barfman, Thanks for your great input. It was very helpful in giving me some idea of what types of fill pressures and speeds, other people are getting. I too found that this AT44 really seems to likes JSB 16's and 18's (especially the 18's). I've only tried a few pellets but the JSB 16's and 18's were so good I think it will be hard to find anything this gun likes better. Of course that may change once I get this modified to the specs. I'm hoping to get. As I recall you did a four port plug on yours and were getting 50 good shots in the 800 fps range. That sounds about what I'm looking for. The current 50 shot string I'm getting is horrible (low of 740 and high of 880) so I think it's going to take a lot of adjustments and shooting to get the tune I want (unless I get really lucky). That's why information from folks like you is so helpful. It gives a person some ideas of what works and what doesn't work and reduces the number of times the gun has to be taken apart and put together again.

I'm hoping to give it another try this afternoon. I just hope the front O-ring on the valve holds out. It's looking kind of shabby with a number of nicks and grooves. I'm planning on replacing it when I finish these tests... if it holds out that long.


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PostPosted: Tue Oct 27, 2015 3:47 pm 
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The o-ring should hold out for now, just make sure to use plenty of silicone grease on it. That tends to keep them healthy enough.

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Mike

FX Streamline .22 - Optisan Mamba Lite 4-16X44
Hammerli Pneuma Elite 10 .22 - Bushnell Elite 4200 4-12X40
Custom Crosman 2240 w/ LW barrel - Vortex Strikefire
Remington AirMaster 77 PAL rated - CenterPoint 3-9X40


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PostPosted: Wed Oct 28, 2015 12:51 am 
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PART TWO:

I was able to try out two more sail sizes today and I think I’m close to the power level I want. The correct tune is a project for another day. The day was overcast, with the temperature about 72 F with no wind. 150 bar fill and using the same equipment and pellets. Still shooting with power adjuster at two turns out. As you recall the .375” sail recorded an incredibly low 175 fps. so I decided to try one closer to .360”.

.360” sail (< .040” of valve diameter) with PA at 2 turns out = 466, 462, 461, 462, 466 fps. Still too low. I must have done the math wrong.

Degassed, disassembled and ground the sail to .350", reassembled, filled to 150 bar.

.350” sail (< .050” of valve diameter) with PA at 2 turns out = 680, 662, 681, 677, 676 fps. Still too low but getting closer so I tried again with the PA at 4 turns out.

.350” sail (< .050” of valve diameter) with PA at 4 turns out = 772, 773,779,783,781,785, 791, 790, 801, 805, 809, 812, 806, 810, 817, 818, 820, 817, 812, 807.

Started to look like rain so I ended the test for the day.

Next time I’ll try a full test from 200 bar to 100 bar and see what the string looks like. I’ve got a feeling it’s still going to be pretty bad if the last 20 rounds I fired today are any indication.

After I do a full test with the CP 14.3’s, I’ll try it again with the JSB 16’s and if time permits with the JSB 18’s, and also try some different power settings. I have a feeling I will shave the sail down to .345” so I will have a little more room to play with the Power Adjuster.


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PostPosted: Thu Oct 29, 2015 10:46 pm 
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PART 3

I shot two more strings through the chrony today, one with PA at 4 turns out and one at PA with 6 turns out. Still using the .350” sail. Both from 200 bar to about 80 bar and using the same equipment and Crosman 14.3 pellets. The day was clear, with the temperature about 75 F with no wind. I got more questions than answers. I’m getting roughly 30 to 38 shots within 5% with all three settings and I’m unable to flatten the curve very much.

PA at 4 turns out. Total of 80 shots. 38 shots within 5%. High of 828 fps.

688, 693, 697, 691, 702, 703, 694, 698, 715, 706, 710, 709, 709, 715, 716, 724, 727, 726, 728, 732, 731, 733, 749, 739, 739,741, 750, 754, 761, 752, 759, 757, 770, 762, 773, 773, 774, 778, (780), 790, 785, 792, 795, 795, 796, 797, 804, 806, 805, 810, 809, 817, 818, 819, 824, 821, 825, 826, 827, 826, 825, 827, (828), 822, 821, 820, 816, 813, 810, 809, 803, 795, 790, 787, (783), 778, 776, 760, 758, 748.

PA at 6 turns out. Total of 55 shots. 32 shots within 5%. High of 860 fps.
***(This is almost the same number of shots I got within 5%, with two turns out on the PA and before adding the sail, with a slightly better HIGH (880 fps).

772, 778, 780, 789, 794, 793, 792, 801, 799, 807, 801, 809, 811, (820), 820, 826, 832, 836, 836, 835, 841, 841, 837 843, 844, 853, 851, 854, 852, 853, 854, 857, 858, 857, (860), 855, 852, 846, 840, 841, 837, 834, 828, 820, (818), 813, 811, 802, 797, 791, 781, 777, 768, 765, 750.


So with the PA at 4 turns out, I got 80 shots with 38 within 5% but with the PA at 6 turns out, I got 55 shots with 32 shots within 5%. On the original shot string without the sail, I got 50+ shots with 30 shots within 5%. In all three strings the HIGH is still in the last 2/3 of the string.

My questions are: Is there a way of flattening the string out more and also bringing the peak of the curve, more toward the center? Do I need to increase the preload on the hammer some more? (I think I can only effectively go one more turn out). Do I need a stiffer hammer spring so I will have more adjustment room? Do I need to shave the sail down a little, to say .345”?

On the first string with the sail, where I used the 4 turns out on the PA, if I started with a lower starting fill pressure (say 170 bar) would that flatten the curve out a little? I know so little about tuning, I’m not sure what to try first.


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PostPosted: Fri Oct 30, 2015 9:55 pm 
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TEST 4:

From yesterday’s results it looked like starting with a lower fill might start the string at a higher fps and have less unusable shots at the beginning and end. Today I shot two more string. The PA was still 6 turns out, still using the .350” sail and Crosman 14.3s. Starting fill pressure was at about 170 bar and ending was about 100 bar.

798, 808, 802 805, 809, (812), 816, 817, 820, 822, 827, 830, 836, 841, 841, 847, 848, 851, 845, 849, (856), 851, 850, 852, 850, 851, 850, 848, 845, 842, 840, 835, 830, 830, 824, 821, (813), 809, 798, 797.

Total of 40 shots with a high of 856 fps and low of 797 fps. The first and last shot were very close (798 and 797). 32 shots within 95% out of 40 shots. The curve looks better, there are fewer unusable shots and less air used. All around the best results for me so far but still not close to the 40 to 50 shots I would like to get.

I’m not sure what my next change should be to get a higher usable shot count. Should I try lowering the fill to around 160 bar? If I do that I think I’ll get less than 40 shots total. Should I turn the PA down one turn to 5 and try filling to 180 bar? Or lastly, should I make the sail a little smaller and start the test over?


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PostPosted: Mon Nov 02, 2015 5:37 am 
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You may want to restrict your transfer port. I'm not sure what size its at in stock .22. Also with a small 180cc reservoir you'll be limited in your shot count . Keep trying , your pretty close to where you want to be.

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PostPosted: Mon Nov 02, 2015 11:14 pm 
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Thanks for the reply Hobbyman. I do have a question about your suggestion to try restricting the transfer port. I thought that by adding a “sail” (mine is .350” which is about .050” smaller than the valve bore) it restricts the air flow through the valve. I was getting a max of about 880 fps without a sail, 175 fps with a .375 sail, about 466 fps with a .360 sail and about 680 fps with a .350” sail. (all with the PA at 2 CCW) So with the .350” sail I’m getting about 23% less air to the TP then before adding a sail (If I did my math correctly). Does that mean that I have reduced the amount of air going through the TP and to the pellet by 23%. It seems logical to me but I do not know all of the mechanics involved so I’m just guessing.

The results from test #4 (PA at 6 CCW, 170 bar fill down to 100 bar) looked encouraging: Total of 40 shots with a high of 856 fps and low of 797 fps. The first and last shot were very close (798 and 797). 32 shots within 95% out of 40 shots.

I have since tried four more tests but without any improvement in the results. Here are the numbers in case someone can make sense out of them and give me an idea of what to try next.

TEST 5:

PA at 5 CCW. Fill to 170 bar and shot down to ??? Didn’t finish test because the numbers looked bad.

753, 755, 758, 758, 767, 760, 767, 771, 777 780, 778, 783, 783, 789, 793, 787, 797, 800, 809, 808, 807, 814, 881 818, 816, 821 …… unk high but even at 821, 5% would be (780) which is ten shots into the string.

PA at 5 CCW. Fill to 160 bar and shot down to ??? Didn’t finish test because the numbers looked bad.

764, 767, 768, 780, 778, 777, 784, 784, 792, 793, 795, 799, 796, 803, 803, 810, 8 1813, 813, 825, 817, 822, 827, 826, 834, 831, 835, 836, 838, 833 …. Unk high but even at 838, 5 % would be 796 which is 11 shots into the string.

TEST 6:

PA at 4 CCW. Fill to 170 bar and shot down to about 80 bar. 70 shots, 36 shots within 96%, High of 822 fps, low was 718 fps. 25 unusable shots at front of string and 9 unusable shots at end of string.

719, 719, 721, 729, 729, 732, 728, 728, 738, 736 740, 745, 741, 746, 752, 751, 750, 705, 753, 762, 762, 763, 771, 771, 777, (779), 782, 785, 786, 787, 788, 791, 792, 792, 799, 803, 803, 803, 806, 807, 813, 811, 813, 818, (822), 815, 816, 821, 820, 819, 814, 812, 808, 803, 801, 800, 792, 787, 788, 780, (783), 775, 771, 758, 751, 749, 738, 733, 720, 718


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PostPosted: Tue Nov 03, 2015 12:03 am 
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Kid.Shelleen wrote:
Thanks for the reply Hobbyman. I do have a question about your suggestion to try restricting the transfer port. I thought that by adding a “sail” (mine is .350” which is about .050” smaller than the valve bore) it restricts the air flow through the valve. I was getting a max of about 880 fps without a sail, 175 fps with a .375 sail, about 466 fps with a .360 sail and about 680 fps with a .350” sail. (all with the PA at 2 CCW) So with the .350” sail I’m getting about 23% less air to the TP then before adding a sail (If I did my math correctly). Does that mean that I have reduced the amount of air going through the TP and to the pellet by 23%. It seems logical to me but I do not know all of the mechanics involved so I’m just guessing.

The results from test #4 (PA at 6 CCW, 170 bar fill down to 100 bar) looked encouraging: Total of 40 shots with a high of 856 fps and low of 797 fps. The first and last shot were very close (798 and 797). 32 shots within 95% out of 40 shots.

I have since tried four more tests but without any improvement in the results. Here are the numbers in case someone can make sense out of them and give me an idea of what to try next.

TEST 5:

PA at 5 CCW. Fill to 170 bar and shot down to ??? Didn’t finish test because the numbers looked bad.

753, 755, 758, 758, 767, 760, 767, 771, 777 780, 778, 783, 783, 789, 793, 787, 797, 800, 809, 808, 807, 814, 881 818, 816, 821 …… unk high but even at 821, 5% would be (780) which is ten shots into the string.

PA at 5 CCW. Fill to 160 bar and shot down to ??? Didn’t finish test because the numbers looked bad.

764, 767, 768, 780, 778, 777, 784, 784, 792, 793, 795, 799, 796, 803, 803, 810, 8 1813, 813, 825, 817, 822, 827, 826, 834, 831, 835, 836, 838, 833 …. Unk high but even at 838, 5 % would be 796 which is 11 shots into the string.

TEST 6:

PA at 4 CCW. Fill to 170 bar and shot down to about 80 bar. 70 shots, 36 shots within 96%, High of 822 fps, low was 718 fps. 25 unusable shots at front of string and 9 unusable shots at end of string.

719, 719, 721, 729, 729, 732, 728, 728, 738, 736 740, 745, 741, 746, 752, 751, 750, 705, 753, 762, 762, 763, 771, 771, 777, (779), 782, 785, 786, 787, 788, 791, 792, 792, 799, 803, 803, 803, 806, 807, 813, 811, 813, 818, (822), 815, 816, 821, 820, 819, 814, 812, 808, 803, 801, 800, 792, 787, 788, 780, (783), 775, 771, 758, 751, 749, 738, 733, 720, 718


Any conclusions from your point of view?


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PostPosted: Tue Nov 03, 2015 3:13 pm 
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My conclusions are that right now, I’m working with two variables, the hammer preload and the starting fill pressure. The other two factors (sail size and pellet weight) are constants. Increasing the preload, increases the first shot speed but reduces the shot count and increasing the starting fill pressure, decreases the first shot speed but increases the shot count. I do not know what influences where the “high shot” occurs in the shot string.

The closest to what I would like is the 6 CCW, fill to 170 bar shooting down to 100 bar, where I got 40 total shots with 32 shots within 95% with a high of 856 almost in the middle of the string. I just don’t know what to do to get that up to say 50 total shots with 40 shots within 95%. Everything I’ve tried so far hasn’t worked.


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PostPosted: Sun Nov 08, 2015 1:02 am 
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I wasn't getting the results I wanted with the .350 sail so I tried a couple of string with a .343" sail. Here are the results:

Test 7: New sail (.343”) added, PA 4CCW, Fill to 175 bar, shot down to 80. 28 shots at 4%, 32 shots at 5%, 38 shots at 6%. High of 840 fps, low of 755 fps. Total of about 53 shots.

755, 754, 760, 763, 767, 769, 771, 776, 780, 786, 789, 791, 796, 797, 801, (808), 806, 806, 815, 818, 817, 818, 824, 825, 824, 826, 829, 832, 839, 828, 831, 835, (840), 837, 832, 830, 824, 824, 823, 819, 818, 816, (806), 804, 800, 789, 789, 780, 776, 771, 766, 762, 749

Test 8: .343” sail, PA 5CCW, Fill to 175 bar, shot down to 80 bar. 27 shots at 4%, 28 shots at 5%, 36 shots at 6 %. High of 859 fps, low of 783. Total of about 43 shots.

782, 790, 800, 798, 808, 808, 809, 810, 810, (824), 819, 826, 831, 883, 840, 839, 841, 839, 844 850, 846, 847, 853, 856, (859), 853, 858, 847, 849, 847, 842, 841, 834, 829, 826, (822), 817, 811, 806, 806, 794, 791, 783

Still can't seem to get the 50 shots within 4%. Got a suggestion on another forum to put in a regulator. I really want to try to get this to work without a regulator but may have to go that route if I can't figure this out.


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PostPosted: Sun Nov 08, 2015 10:11 am 
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Thank you for your investigation and testing. It will come useful for future projects.

Would you have pictures of the sails you tested?

Alex

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Steyr hunting 5 automatic
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AlEx Custom gun .22 (JezX built masterpiece) :)
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PostPosted: Sun Nov 08, 2015 11:37 am 
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Here is another adjustable variable for power and shot count, the power stem. The high powered stem is the one at the right. The other 2 are: factor low power and the one I turned down to get the speeds I wanted. The stem in the middle is only .020" IIRC smaller than the >500fps stem, yet gave 960fps with 10.5gr. .177 pellets - with the sail and plugged ports. the full power stem on the right, is an air hog.
The 44's system is similar.

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