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All Springer/NP/PCP Air Gun Discussion General => PCP/CO2/HPA Air Gun Gates "The Darkside" => Topic started by: James340 on February 04, 2023, 09:14:55 PM
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I wanted to get 550/600 fps.I started at 2200 psi and it was shooting 300 with the hammer spring adjusted 7 turns in from flush but velocity steadily went up as pressure went down.it hit 600 at around 1800 psi.I did some HS adjustments and different psi.I get 578 fps to 630 fps at a start pressure of 1200 psi and ending 800 psi and HS adjuster flush with receiver.I wonder if a lighter poppet/valve spring would help to flatten the curve.
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I started at 3000 psi ( I have a compressor ) and here is my 2027 chrono results.
I forget what HS settings other than I was trying for two mags or 24 shots.
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I started at 3000 psi ( I have a compressor ) and here is my 2027 chrono results.
I forget what HS settings other than I was trying for two mags or 24 shots.
I am after 550/600 fps.More velocity is very loud and unnecessary for my plinking.
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I use a Buck Rail 1322 moderator - it is neighbor friendly
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I use a Buck Rail 1322 moderator - it is neighbor friendly
I will continue to test/play with HS adjustments and see what happens.I thought someone may have worked on poppet tuning with springs.
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I started at 3000 psi ( I have a compressor ) and here is my 2027 chrono results.
I forget what HS settings other than I was trying for two mags or 24 shots.
I believe it was 2 mags for 1200 psi down to 800 at the 580 fps to 630 back to 580 then it was in free fall
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I used Winchester hp.At 1200 psi it shoots 600 fps for 20 shots then started dropping 10 fps each shot.So I get 2 mags of very consistent shots.I have been hand pumping this gun since it is so easy.
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If you are not trying to increase muzzle energy, you can also increase the tension of the valve return spring. You can use a heavier spring, or potentially use washers to put more preload to that spring.
The theory is to make tank pressure less of a factor compared to the total valve opening/closing dynamic.
Given a fixed hammer spring tension, this will decrease muzzle energy because the valve will be harder to open and close faster.
Also, based on my own experience down tuning unregulated PCP pistols, reducing hammer spring tension shifts the velocity curve toward the lower pressure side, and it also spreads that curve over a wider range of pressure and still get relatively consistent muzzle velocity.
James340's numbers are very consistent with my Brocock AimX .177 PCP pistol despite the Brocock and the Beeman 2027 being unrelated.
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If you are not trying to increase muzzle energy, you can also increase the tension of the valve return spring. You can use a heavier spring, or potentially use washers to put more preload to that spring.
The theory is to make tank pressure less of a factor compared to the total valve opening/closing dynamic.
Given a fixed hammer spring tension, this will decrease muzzle energy because the valve will be harder to open and close faster.
Also, based on my own experience down tuning unregulated PCP pistols, reducing hammer spring tension shifts the velocity curve toward the lower pressure side, and it also spreads that curve over a wider range of pressure and still get relatively consistent muzzle velocity.
James340's numbers are very consistent with my Brocock AimX .177 PCP pistol despite the Brocock and the Beeman 2027 being unrelated.
I think I have settled on 1000 psi+- shoot 12 shots and pump it 12& repeat 😜 It put 4 out of 10 RWS Hobby in a 1/2" hole at 40 yards on a windy day.7 out of 10 was a 1 1/2" group.Thanks for the poppet tuning idea that makes sense to increase pressure on it.I didn't think of it 🤔 I originally wanted a higher shot count but accuracy is primarily my interest
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This is what mine did. I installed a different hammer spring.
The gage on my 2027 reads 100 psi low so 900 psi is actually 1000 psi.
Beeman 2027 R10 7.0 4.51
73 mm spring flush 1-2-2023
Chinese crono
psi fps
509
1000 499
502
525
532
505
525
532
532
950 545
538
541
554
900 554
551
561
558
571
558
571
568
574
800 591
587
800 594
584
604
610
700 607
700 594
700 600
594
597
594
587
584
600 577
571
568
564
554
551
500 545
538
528
522
400 512
502
495
482
476
300 463
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This is what mine did. I installed a different hammer spring.
The gage on my 2027 reads 100 psi low so 900 psi is actually 1000 psi.
Beeman 2027 R10 7.0 4.51
73 mm spring flush 1-2-2023
Chinese crono
psi fps
509
1000 499
502
525
532
505
525
532
532
950 545
538
541
554
900 554
551
561
558
571
558
571
568
574
800 591
587
800 594
584
604
610
700 607
700 594
700 600
594
597
594
587
584
600 577
571
568
564
554
551
500 545
538
528
522
400 512
502
495
482
476
300 463
I know the gauge is not accurate but use it as reference.I did change the factory spring.I read one of the threads that recommended a 10 mm od 1 mm wire 75 mm long.Maybe you?I cut it a little longer.I get a really consistent 20 shots and then it started losing velocity.I had hoped for more but I am pleased with it especially for the price
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I used the same spring from AliExpress cut to 73mm.
Sometimes mine puts 10 pellets into 1 ragged hole at 18 yards using R10 7.0 gr wadcutters.
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I wanted to get 550/600 fps.I started at 2200 psi and it was shooting 300 with the hammer spring adjusted 7 turns in from flush but velocity steadily went up as pressure went down.it hit 600 at around 1800 psi.I did some HS adjustments and different psi.I get 578 fps to 630 fps at a start pressure of 1200 psi and ending 800 psi and HS adjuster flush with receiver.I wonder if a lighter poppet/valve spring would help to flatten the curve.
Robert Sterne has a pcp post about finding the "knee" of the shot curve and tuning to it. The math is challenging, but the concept is easy to grasp. As best I can tell it is a balance between the hammer, valve, and tp at a given pressure. I've read it several times and I'll need a few more.
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FYI finding the velocity knee pertains to regulated PCPs. The Beeman 2027 is unregulated. If it will accept a bstaley O-ring buffer, that's a proven way to produce broad shot strings at modest velocities.
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If you are not trying to increase muzzle energy, you can also increase the tension of the valve return spring. You can use a heavier spring, or potentially use washers to put more preload to that spring.
The theory is to make tank pressure less of a factor compared to the total valve opening/closing dynamic.
Given a fixed hammer spring tension, this will decrease muzzle energy because the valve will be harder to open and close faster.
Also, based on my own experience down tuning unregulated PCP pistols, reducing hammer spring tension shifts the velocity curve toward the lower pressure side, and it also spreads that curve over a wider range of pressure and still get relatively consistent muzzle velocity.
James340's numbers are very consistent with my Brocock AimX .177 PCP pistol despite the Brocock and the Beeman 2027 being unrelated.
This is the kind of hands-on experimentation I love to read about. The math is tough for me, but your practical explanation is easy to grasp.
Food for thought, I saw a video of a British tuner who made a numbered 'click dial' for his hammer spring adjuster (Crosman 2240 safepac pcp, I believe). He started shooting with the hammer adjuster at higher tension and readjusted it between shots to keep fps consistent as the psi fell. A pretty neat trick and it worked well!
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FYI finding the velocity knee pertains to regulated PCPs. The Beeman 2027 is unregulated. If it will accept a bstaley O-ring buffer, that's a proven way to produce broad shot strings at modest velocities.
Thanks for the correction, Jason! I DO need to read that post a few more times!
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Someone please post a link to the "bstaley O-ring buffer".
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I am not sure but I think the "bstaley O-ring buffer" is putting a o-ring in front of the hammer to sort of cushion the hammer strike.
I have not done this on any of my PCP's - I forget what this hammer noise is called.
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FYI finding the velocity knee pertains to regulated PCPs. The Beeman 2027 is unregulated. If it will accept a bstaley O-ring buffer, that's a proven way to produce broad shot strings at modest velocities.
Thanks for the suggestion.I had not considered that but it makes sense.Do you think the valve should get more preload or a stiffer spring?I googled "BStaley o ring"I did this to a Chaser and it is so much better.
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Someone please post a link to the "bstaley O-ring buffer".
I googled it and it is a stack of o rings against the valve to reduce hammer bounce which waste air.
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FYI finding the velocity knee pertains to regulated PCPs. The Beeman 2027 is unregulated. If it will accept a bstaley O-ring buffer, that's a proven way to produce broad shot strings at modest velocities.
Thanks for the suggestion.I had not considered that but it makes sense.Do you think the valve should get more preload or a stiffer spring?I googled "BStaley o ring"I did this to a Chaser and it is so much better.
The BStaley o-ring mod has the same effect as increasing the return valve spring tension and buffering the hammer bounce from re-opening the valve. It kills two birds with one stone. However, not all hammer-valve designs can use the BStaley o-ring mod.
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FYI finding the velocity knee pertains to regulated PCPs. The Beeman 2027 is unregulated. If it will accept a bstaley O-ring buffer, that's a proven way to produce broad shot strings at modest velocities.
Thanks for the suggestion.I had not considered that but it makes sense.Do you think the valve should get more preload or a stiffer spring?I googled "BStaley o ring"I did this to a Chaser and it is so much better.
The BStaley o-ring mod has the same effect as increasing the return valve spring tension and buffering the hammer bounce from re-opening the valve. It kills two birds with one stone. However, not all hammer-valve designs can use the BStaley o-ring mod.
I think I will try it.I found a good combination for 12 shots at 600 fps but I would like more shots
-
FYI finding the velocity knee pertains to regulated PCPs. The Beeman 2027 is unregulated. If it will accept a bstaley O-ring buffer, that's a proven way to produce broad shot strings at modest velocities.
Thanks for the suggestion.I had not considered that but it makes sense.Do you think the valve should get more preload or a stiffer spring?I googled "BStaley o ring"I did this to a Chaser and it is so much better.
The BStaley o-ring mod has the same effect as increasing the return valve spring tension and buffering the hammer bounce from re-opening the valve. It kills two birds with one stone. However, not all hammer-valve designs can use the BStaley o-ring mod.
I think I will try it.I found a good combination for 12 shots at 600 fps but I would like more shots
Good luck James! Please post your results on how the mod performed in your 2027.
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FYI finding the velocity knee pertains to regulated PCPs. The Beeman 2027 is unregulated. If it will accept a bstaley O-ring buffer, that's a proven way to produce broad shot strings at modest velocities.
Thanks for the suggestion.I had not considered that but it makes sense.Do you think the valve should get more preload or a stiffer spring?I googled "BStaley o ring"I did this to a Chaser and it is so much better.
The BStaley o-ring mod has the same effect as increasing the return valve spring tension and buffering the hammer bounce from re-opening the valve. It kills two birds with one stone. However, not all hammer-valve designs can use the BStaley o-ring mod.
I think I will try it.I found a good combination for 12 shots at 600 fps but I would like more shots
Good luck James! Please post your results on how the mod performed in your 2027.
I installed a 3x13 mm o ring in a Chaser and my shot count went from 40 to 85.425 fps for first shot 488 for the 81 shot.that is at 65 degrees might be better when it warms up.
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FYI finding the velocity knee pertains to regulated PCPs. The Beeman 2027 is unregulated. If it will accept a bstaley O-ring buffer, that's a proven way to produce broad shot strings at modest velocities.
Thanks for the suggestion.I had not considered that but it makes sense.Do you think the valve should get more preload or a stiffer spring?I googled "BStaley o ring"I did this to a Chaser and it is so much better.
The BStaley o-ring mod has the same effect as increasing the return valve spring tension and buffering the hammer bounce from re-opening the valve. It kills two birds with one stone. However, not all hammer-valve designs can use the BStaley o-ring mod.
I think I will try it.I found a good combination for 12 shots at 600 fps but I would like more shots
Good luck James! Please post your results on how the mod performed in your 2027.
I installed a 3x13 mm o ring in a Chaser and my shot count went from 40 to 85.425 fps for first shot 488 for the 81 shot.that is at 65 degrees might be better when it warms up.
I didn't realize the hammer drove the poppet that far! I've never seen the guts of a Chaser but assuming it's like a Crosman that's driving the stem flush (or more with momentum) for a 3mm o-ring to make that drastic of a difference. My thoughts were the valve only opened a few mm before pressure and valve spring forced it closed again.
Love this place, learn something every time I'm here!
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FYI finding the velocity knee pertains to regulated PCPs. The Beeman 2027 is unregulated. If it will accept a bstaley O-ring buffer, that's a proven way to produce broad shot strings at modest velocities.
Thanks for the suggestion.I had not considered that but it makes sense.Do you think the valve should get more preload or a stiffer spring?I googled "BStaley o ring"I did this to a Chaser and it is so much better.
The BStaley o-ring mod has the same effect as increasing the return valve spring tension and buffering the hammer bounce from re-opening the valve. It kills two birds with one stone. However, not all hammer-valve designs can use the BStaley o-ring mod.
I think I will try it.I found a good combination for 12 shots at 600 fps but I would like more shots
Good luck James! Please post your results on how the mod performed in your 2027.
I installed a 3x13 mm o ring in a Chaser and my shot count went from 40 to 85.425 fps for first shot 488 for the 81 shot.that is at 65 degrees might be better when it warms up.
I didn't realize the hammer drove the poppet that far! I've never seen the guts of a Chaser but assuming it's like a Crosman that's driving the stem flush (or more with momentum) for a 3mm o-ring to make that drastic of a difference. My thoughts were the valve only opened a few mm before pressure and valve spring forced it closed again.
Love this place, learn something every time I'm here!
I put a 2.4x17 mm o ring in the Beeman 2027.Full pressure fill results are lower velocity but I filled to 1500 psi and it shoots 625 fps up to 660 and then back down to 625 for 24 shots.I use a hand pump to fill& this time takes 15-20 strokes.It is not a good pump but works fine for the modest pressure