Huben GK1 on Helium

[Azycray]

A little background first. I was cranking up the power the other day as stated in the owners manual, a quarter turn with each shot. With a Donny FL Emperor on it, from the factory it was whisper quiet, still using the air that it came with. As I shot in rapid succession with a quarter turn after each the power started going up noticeably. I was getting excited and then it ran out of gas so to speak. The last shot there was a noticeable difference, something like a clang or thump combined, I wasn't watching and I had dropped below the recommended minimum pressure. So I went and filled it up to about 4800psi with helium and took it outside again, the first shot was much louder than I had expected. But not from the gas release, it was supersonic. Well I couldn't do that any more without one of the neighbors pitching a fit. so that led to the test I'm about to describe. Nothing special, in my shed to muffle the sound further and also eliminate the sonic crack because of the short distance between the muzzle and the log I shot it into. This time I filled to just over the line into red at about 35.5 MPa or 5149 psi The first shot was 1368 FPS, 2nd shot was 4786 psi and 1322 FPS, 3rd shot was 4424 PSI with an ERR for speed, 4th shot was 4061 PSI and 1230 FPS, 5th shot was 3625 PSI and 1174 FPS. After that it dropped to subsonic. Even after it went subsonic with the Emperor it was still abnormally loud. So I have a question, do you have to degas to adjust the other direction? With my FX Impact, and I forget which way it was but you could only go in one direction without degassing. The manual said a quarter turn to increase power but didn't say anything about lowering power. I'd rather not degas if I don't have to.

 

[Nutcracker]

WOW, those are some crazy speeds. I never degassed mine to lower power. I try to do most of my adjusting at lower fill pressure. But have adjusted at full fill both to increase & to lower. I also do 1/4 turn increments. I never heard or read to degauss to lower pressure. I think that is what some regulated guns may require to reduce damage to the reg. These guns have no reg. Well, they do have a regulated one now, but most of us don't have that.

 

[MrP]

What weight of projectiles were you shooting?

 

[Azycray]

What weight of projectiles were you shooting?

Yeah sorry I forgot to mention that. I was using 25.4 grain FX pellets, bulletcentral.com had a screaming good deal for a while, not sure if they still do but I think it was about $11 for a 350 tin so I got 5. I had also got a bunch of the .357's for the Rattler. They were also about $11 but 100 to a tin. I do have some slugs on the way I will be testing end of the week. Some 34 & 36 grain AVS slugs.

 

[JaceSpace1369]

A little background first. I was cranking up the power the other day as stated in the owners manual, a quarter turn with each shot. With a Donny FL Emperor on it, from the factory it was whisper quiet, still using the air that it came with. As I shot in rapid succession with a quarter turn after each the power started going up noticeably. I was getting excited and then it ran out of gas so to speak. The last shot there was a noticeable difference, something like a clang or thump combined, I wasn't watching and I had dropped below the recommended minimum pressure. So I went and filled it up to about 4800psi with helium and took it outside again, the first shot was much louder than I had expected. But not from the gas release, it was supersonic. Well I couldn't do that any more without one of the neighbors pitching a fit. so that led to the test I'm about to describe. Nothing special, in my shed to muffle the sound further and also eliminate the sonic crack because of the short distance between the muzzle and the log I shot it into. This time I filled to just over the line into red at about 35.5 MPa or 5149 psi The first shot was 1368 FPS, 2nd shot was 4786 psi and 1322 FPS, 3rd shot was 4424 PSI with an ERR for speed, 4th shot was 4061 PSI and 1230 FPS, 5th shot was 3625 PSI and 1174 FPS. After that it dropped to subsonic. Even after it went subsonic with the Emperor it was still abnormally loud. So I have a question, do you have to degas to adjust the other direction? With my FX Impact, and I forget which way it was but you could only go in one direction without degassing. The manual said a quarter turn to increase power but didn't say anything about lowering power. I'd rather not degas if I don't have to.

Your first shot put out 105.5fpe...that's insane.

 

[Felinis]

There is a YouTube shooting video where the guy claims "Most Powerful Air Pistol I Have Ever Tested.":

He tested his CO2 pistol with a closed chronograph system and got incredible velocities. It turned out that he was outside on a humid day and his pistol was expelling a cloud of moisture with each shot.

The fast-moving gas cloud was deceiving the chrony into detecting the cloud's speed instead of the pellet's.

 

[weevil]

Congrats on the GK1 record! Which I’m sure you will beat later with heavier ammo. I recall someone shooting 90fpe with a 34g JSB on air at 360bar. Slightly higher than any of the slugs he tried due to less friction.

 

[weevil]

No need to degas to adjust either way but spring may take a couple shots to settle.

 

[Azycray]

Congrats on the GK1 record! Which I’m sure you will beat later with heavier ammo. I recall someone shooting 90fpe with a 34g JSB on air at 360bar. Slightly higher than any of the slugs he tried due to less friction.

Hmmm, we shall see. My experience with an Extreme .457 and my very custom Impact .247 has been the heavier, the slower. It seems the heavier would also be longer which should give more friction. I will certainly let you know what happens with slugs that are due to arrive tomorrow. I also have some testing to do with my also very new Rattler .357. I just haven't had the time to take it to an appropriate place for some proper testing. But I might try one round in the shed as long as I have it set up. I thought I had escaped this PCP addiction, I went 3-4 years without a purchase and little presence on the forum. Then I fell off the wagon.

 

[weevil]

Hmmm, we shall see. My experience with an Extreme .457 and my very custom Impact .247 has been the heavier, the slower. It seems the heavier would also be longer which should give more friction. I will certainly let you know what happens with slugs that are due to arrive tomorrow. I also have some testing to do with my also very new Rattler .357. I just haven't had the time to take it to an appropriate place for some proper testing. But I might try one round in the shed as long as I have it set up. I thought I had escaped this PCP addiction, I went 3-4 years without a purchase and little presence on the forum. Then I fell off the wagon.

Slower, yes, but more fpe. Plus, if you are shooting less than 1100fps, you will not get the sonic crack, which no moderator can prevent.

 

[Nomadic Pirate 66]

As mentioned with ammo in the 40gr + you should stay subsonic while increasing FPE

With mine on the same setting I shoot the 34gr at 920 fps and the 43gr at 870 fps for a difference of almost 10 FPE

 

[steve-l]

A little background first. I was cranking up the power the other day as stated in the owners manual, a quarter turn with each shot. With a Donny FL Emperor on it, from the factory it was whisper quiet, still using the air that it came with. As I shot in rapid succession with a quarter turn after each the power started going up noticeably. I was getting excited and then it ran out of gas so to speak. The last shot there was a noticeable difference, something like a clang or thump combined, I wasn't watching and I had dropped below the recommended minimum pressure. So I went and filled it up to about 4800psi with helium and took it outside again, the first shot was much louder than I had expected. But not from the gas release, it was supersonic. Well I couldn't do that any more without one of the neighbors pitching a fit. so that led to the test I'm about to describe. Nothing special, in my shed to muffle the sound further and also eliminate the sonic crack because of the short distance between the muzzle and the log I shot it into. This time I filled to just over the line into red at about 35.5 MPa or 5149 psi The first shot was 1368 FPS, 2nd shot was 4786 psi and 1322 FPS, 3rd shot was 4424 PSI with an ERR for speed, 4th shot was 4061 PSI and 1230 FPS, 5th shot was 3625 PSI and 1174 FPS. After that it dropped to subsonic. Even after it went subsonic with the Emperor it was still abnormally loud. So I have a question, do you have to degas to adjust the other direction? With my FX Impact, and I forget which way it was but you could only go in one direction without degassing. The manual said a quarter turn to increase power but didn't say anything about lowering power. I'd rather not degas if I don't have to.

Those are some impressive numbers. How certain are you they are real? What caliber is your GK1? I am assuming .25. Lastly, why are you refilling with Helium? Helium is a lot more expensive than air and other than being dry, offer no other advantage. I use the FSB 25.4 gr pellet and limit my speed to 720 FPS because that allows a uniform speed for a whole magazine (17). After one magazine, my gun pressure has dropped from 300 bar to 220 bar. I then recharge the gun back to 300 bar.

 

[Airgun-hobbyist]

Those are some impressive numbers. How certain are you they are real? What caliber is your GK1? I am assuming .25. Lastly, why are you refilling with Helium? Helium is a lot more expensive than air and other than being dry, offer no other advantage. I use the FSB 25.4 gr pellet and limit my speed to 720 FPS because that allows a uniform speed for a whole magazine (17). After one magazine, my gun pressure has dropped from 300 bar to 220 bar. I then recharge the gun back to 300 bar.

Those are some good numbers which could certainly be the norm with a dry gas like Helium. The way the two valves operate in the Huben a dry gas may allow them to work faster without the "inference" of properties associated with compressed air.

On another note regarding the use of a chronograph, to avoid any outside influence, I like the chronograph set back to a measured 10 yards to test with. Then if need be I can compare those numbers with a few shots taken at the muzzle, 1 foot away.

 

[weevil]

Those are some impressive numbers. How certain are you they are real? What caliber is your GK1? I am assuming .25. Lastly, why are you refilling with Helium? Helium is a lot more expensive than air and other than being dry, offer no other advantage. I use the FSB 25.4 gr pellet and limit my speed to 720 FPS because that allows a uniform speed for a whole magazine (17). After one magazine, my gun pressure has dropped from 300 bar to 220 bar. I then recharge the gun back to 300 bar.

Helium offers a substantial advantage in power because its atomic mass is so small relative to the constituents of air. Therefore much more energy is devoted to the projectile.

Helium in PCPs - Why? - Airguns & Guns Forum

Helium in PCPs - Why?, Air guns, Airgun Forum

www.gatewaytoairguns.org

 

[Azycray]

Those are some impressive numbers. How certain are you they are real? What caliber is your GK1? I am assuming .25. Lastly, why are you refilling with Helium? Helium is a lot more expensive than air and other than being dry, offer no other advantage. I use the FSB 25.4 gr pellet and limit my speed to 720 FPS because that allows a uniform speed for a whole magazine (17). After one magazine, my gun pressure has dropped from 300 bar to 220 bar. I then recharge the gun back to 300 bar.

I've been using the same chronograph for probably 20 years and have no reason to suspect it is not indicating in a reasonable range of variation. I have the .22 HK1 which I mistakenly ordered instead of the .25 but they would not take it back and I didn't want to deal with selling and doing it over. Helium is lighter than air. Air has weight and it's hard to imagine but it takes some of the pressure/energy to move the air. Helium moves faster through the valve, transfer port etc. As far as cost goes, I get 6k tanks from a welding supply and don't find it cost prohibitive. I like the extra performance, but that doesn't mean I will leave this set at this high of a power setting. But I have the option to crank it up whenever I want.

 

[Azycray]

Those are some good numbers which could certainly be the norm with a dry gas like Helium. The way the two valves operate in the Huben a dry gas may allow them to work faster without the "inference" of properties associated with compressed air.

On another note regarding the use of a chronograph, to avoid any outside influence, I like the chronograph set back to a measured 10 yards to test with. Then if need be I can compare those numbers with a few shots taken at the muzzle, 1 foot away.

The owners manual for the Chrony states you only need to put some distance between the chrony and the muzzle blast for the more powerful weapons. I wasn't even using the diffuses or whatever you call them, I have a shop light right above so the sensor don't know the difference. It was probably 2-3 feet in front.

 

[beerthief]

"For those of you concerned about the practicality of using Helium, all I can say is that it has the ability to move through a standard Buna Nitrile O-ring very easily.... While you might be able to do some testing, the gun would lose a lot of its pressure overnight, right through the O-rings.... I know there are other materials that can prevent this, but I have no experience with them to make any recommendations.... Plus, of course, Helium is rare and expensive.... "
IF you fill the gun and shoot ALL available pressure but then you lose the rest overnight ? shooting 300 bar to 220 bar then the rest leaks out ? maybe your cost is misfigured ?

 

[Azycray]

"For those of you concerned about the practicality of using Helium, all I can say is that it has the ability to move through a standard Buna Nitrile O-ring very easily.... While you might be able to do some testing, the gun would lose a lot of its pressure overnight, right through the O-rings.... I know there are other materials that can prevent this, but I have no experience with them to make any recommendations.... Plus, of course, Helium is rare and expensive.... "
IF you fill the gun and shoot ALL available pressure but then you lose the rest overnight ? shooting 300 bar to 220 bar then the rest leaks out ? maybe your cost is misfigured ?

I haven't experienced anything close to that. I have left my rifles untouched some times for over a year and still have pressure. Yes they lose some but not enough to worry about. I started using helium about 8 years ago so take it for what it's worth.

 

[beerthief]

I haven't experienced anything close to that. I have left my rifles untouched some times for over a year and still have pressure. Yes they lose some but not enough to worry about. I started using helium about 8 years ago so take it for what it's worth.

that's what i get for reading a post and not doing my research . my bad !

 

[Azycray]

that's what i get for reading a post and not doing my research . my bad !

No worries brother, just don't steal my beer and we be good.