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All Springer/NP/PCP Air Gun Discussion General => American/U.S. Air Gun Gates => Crosman-Benjamin Air Gun Gate => Topic started by: joklak on June 24, 2013, 12:36:57 AM

Title: realistic 2240 power expectations
Post by: joklak on June 24, 2013, 12:36:57 AM
I have seen some people claim they can get over 1000fps out of a modded 2240.  I dont have a chrony but I have done some valve mods and bolt mods and I know that it does not have nearly as much power as my .22 npss which I'm pretty sure is not shooting 1000fps so I was just wondering what kind of power can I really expect from a modded 2240?
Title: Re: realistic 2240 power expectations
Post by: UCChris on June 24, 2013, 12:46:43 AM
I have seen some people claim they can get over 1000fps out of a modded 2240.  I dont have a chrony but I have done some valve mods and bolt mods and I know that it does not have nearly as much power as my .22 npss which I'm pretty sure is not shooting 1000fps so I was just wondering what kind of power can I really expect from a modded 2240?

I know there is a guy here on GTA that is slinging lead at 800ish fps with a modded 2240.
Title: Re: realistic 2240 power expectations
Post by: grumpy on June 24, 2013, 06:36:07 AM
Its not hard to get 20 fpe with a 2240. Course thats probably not gonna happen without an HPA conversion. Personally my best power from a 22xx gun was about 28 fpe. I have know folks to get in the mid 40 fpe range, but were talking about serious modifying.
Title: Re: realistic 2240 power expectations
Post by: joklak on June 24, 2013, 08:53:54 AM
Its not hard to get 20 fpe with a 2240. Course thats probably not gonna happen without an HPA conversion. Personally my best power from a 22xx gun was about 28 fpe. I have know folks to get in the mid 40 fpe range, but were talking about serious modifying.

I was hoping to get between 16-18 fpe.  I figure that should be pretty good for most of the critters that come into my back yard.   So far  I have angled the valve port, cut a few of the threaeds off of the valve, recontoured the flats spots on the valve needle, made an extended bolt probe and installed a 14.5" barrel.
Title: Re: realistic 2240 power expectations
Post by: Flyboy on June 24, 2013, 10:07:35 AM
Are you guys serious? When looking at modified 2250s I thought getting around 11.5 fpe was pushing the thing to its absolute limits (and not just because it's a tad under the UK legal limit), considering it's already (but only) between 6-8 fpe as standard. You're seriously saying that a 5-5.5 fpe pistol can be taken up to 40+ fpe!?

Or have I once again been bitten by the U.S. vs UK power limits conflict? If so, what is the standard power of a stock 2240 and 2250, in the U.S.?
Title: Re: realistic 2240 power expectations
Post by: JBird on June 24, 2013, 10:53:00 AM
15 FPE is easy with a few mods.  I've got a 2240 with a 12" barrel, HiPac conversion, a few simple valve mods and heavier hammer spring and it's at 15 FPE.  My 2400 with the exact same mods with an 18" barrel is at 20 FPE and with the 24" barrel it was right at 25 FPE.  With HPA barrel length gets you more energy than just about any other mod. 
Title: Re: realistic 2240 power expectations
Post by: cwlongshot on June 24, 2013, 11:08:47 AM
I agree. I certainly an not hollering foul. But to boost power EIGHT FOLD is something I would need to see to believe. I would have to say if done the look would be as far from a 2240 hand gun as one could possible get.  Not Tring to rustle any feathers. But I look at it this way, someone says they want a bit more power from a 1976 Pinto and someone else
Answers I got 800 horse and sub 10 sec quarter mile times from mine. That's just not a realistic expectation for most people. ;) Doable... Sure with enough time money and expertise. Will the avg guy do it? Heck no! ;)

I'm surely no expert, but a better bolt probe, boss valve, playing with springs a bit and a little longer barrel. (Assuming your wanting a pistol as you started with a 2240 NOT a 2260) I would say about 15/16 fpe would be about what you would see. And that's still quite a boost for the 5/6 fpe it is stock!

CW
Title: Re: realistic 2240 power expectations
Post by: Hallucinosis on June 24, 2013, 05:39:38 PM
At those power levels it's more about tuning for fun as a challenge than the practicality of the matter; it's like taking a $100-125 Mosin-Nagant and modifying it until it reaches the point where it's an accurate target rifle, when it would be cheaper, easier, and faster to just buy a better and more modern off-the-shelf rifle that already has a good trigger, floated barrel, scope mounts, etc. It's really a labor of love and not something that's for everyone, but it really seems like the point is to overcome the challenge of getting so much out of the platform. Compared to car tuning, it's a cheap hobby.

I got into modifying my Crosman 1377 because I wanted more out of it. I ended up spending enough on it that I don't really want to think about that, but nowhere near as much time, money, and energy as others have invested in their setups. That said, I had a lot of fun doing it and learned some things, so it was worth it.

I work as a SSE and it feels a lot like code optimization. It's a rewarding experience for me.
Title: Re: realistic 2240 power expectations
Post by: grumpy on June 24, 2013, 06:24:38 PM
Its not hard to increase power to the levels i mentioned. 20 fpe is simple with a barrel, valve and breech/bolt swap. Slap a hipac on about 1500 ish psi and you should be somewhere between 15-20 fpe. A power adjuster will make tuning fairly easy.

I would probably called foul on 30-40 fpe claims to, until I went over to the CAPOF forum. Those guys are wizards at what they can do with the lowely 22XX gun.

For the record I have modded no less then 20 of these guns, its great fun.

This one I cal Frankengun. I have more cash in it then id like to admit, but then again the fun of it was building MY gun :)
Currently its setup to get about 130 shots at roughly 13 fpe.
(http://www.airgunsforum.com/picture.php?albumid=1&pictureid=200)

This is another one of my contraptions.
(http://www.airgunsforum.com/picture.php?albumid=6&pictureid=185)


This was a 2240 that I added an mrod trigger, 24" barrel, TKO, Boss valve. You cannot see it in this pic but its powered by a Hipac at about 1800 PSI. She shot at about 28 fpe and would regularly shoot under 1/2" at 50 yards.
(http://www.airgunsforum.com/picture.php?albumid=1&pictureid=4)

Dave
Title: Re: realistic 2240 power expectations
Post by: rsterne on June 24, 2013, 06:34:28 PM
The biggest limit with a 2240 is barrel length, the second biggest limit is CO2.... Put a 24" barrel on it, a few mods, run it on HPA, and it becomes a Disco.... I have modded a Disco to 53 FPE in .22 cal, over 100 FPE in .25 cal, and 133 FPE in 9mm.... If you're talking a shorter barrel and leaving it on CO2, then give your head a shake, it ain't gonna happen....

Bob
Title: Re: realistic 2240 power expectations
Post by: silent_airman on June 24, 2013, 06:42:38 PM
Wow, you guys are way over my head. I just like shooting small holes in paper and murdering soda cans.  ::)
Title: Re: realistic 2240 power expectations
Post by: cwlongshot on June 24, 2013, 06:46:06 PM
The biggest limit with a 2240 is barrel length, the second biggest limit is CO2.... Put a 24" barrel on it, a few mods, run it on HPA, and it becomes a Disco.... I have modded a Disco to 53 FPE in .22 cal, over 100 FPE in .25 cal, and 133 FPE in 9mm.... If you're talking a shorter barrel and leaving it on CO2, then give your head a shake, it ain't gonna happen....

Bob

(http://img.photobucket.com/albums/v465/CWLONGSHOT/Graemlins/what.gif)(http://img.photobucket.com/albums/v465/CWLONGSHOT/Graemlins/what.gif)(http://img.photobucket.com/albums/v465/CWLONGSHOT/Graemlins/what.gif)(http://img.photobucket.com/albums/v465/CWLONGSHOT/Graemlins/what.gif)(http://img.photobucket.com/albums/v465/CWLONGSHOT/Graemlins/what.gif)(http://img.photobucket.com/albums/v465/CWLONGSHOT/Graemlins/what.gif)(http://img.photobucket.com/albums/v465/CWLONGSHOT/Graemlins/what.gif)(http://img.photobucket.com/albums/v465/CWLONGSHOT/Graemlins/what.gif)(http://img.photobucket.com/albums/v465/CWLONGSHOT/Graemlins/bowdown.gif)(http://img.photobucket.com/albums/v465/CWLONGSHOT/Graemlins/bowdown.gif)(http://img.photobucket.com/albums/v465/CWLONGSHOT/Graemlins/bowdown.gif)(http://img.photobucket.com/albums/v465/CWLONGSHOT/Graemlins/bowdown.gif)(http://img.photobucket.com/albums/v465/CWLONGSHOT/Graemlins/bowdown.gif)(http://img.photobucket.com/albums/v465/CWLONGSHOT/Graemlins/bowdown.gif)(http://img.photobucket.com/albums/v465/CWLONGSHOT/Graemlins/bowdown.gif)(http://img.photobucket.com/albums/v465/CWLONGSHOT/Graemlins/bowdown.gif)(http://img.photobucket.com/albums/v465/CWLONGSHOT/Graemlins/bowdown.gif)(http://img.photobucket.com/albums/v465/CWLONGSHOT/Graemlins/bowdown.gif)
  I would LOVE to read about the 22 disco mods... do you have any posts about it?

CW
Title: Re: realistic 2240 power expectations
Post by: cherokeesteve on June 24, 2013, 08:12:37 PM
Its not hard to increase power to the levels i mentioned. 20 fpe is simple with a barrel, valve and breech/bolt swap. Slap a hipac on about 1500 ish psi and you should be somewhere between 15-20 fpe. A power adjuster will make tuning fairly easy.

I would probably called foul on 30-40 fpe claims to, until I went over to the CAPOF forum. Those guys are wizards at what they can do with the lowely 22XX gun.

For the record I have modded no less then 20 of these guns, its great fun.

This one I cal Frankengun. I have more cash in it then id like to admit, but then again the fun of it was building MY gun :)
Currently its setup to get about 130 shots at roughly 13 fpe.
(http://www.airgunsforum.com/picture.php?albumid=1&pictureid=200)

This is another one of my contraptions.
(http://www.airgunsforum.com/picture.php?albumid=6&pictureid=185)


This was a 2240 that I added an mrod trigger, 24" barrel, TKO, Boss valve. You cannot see it in this pic but its powered by a Hipac at about 1800 PSI. She shot at about 28 fpe and would regularly shoot under 1/2" at 50 yards.
(http://www.airgunsforum.com/picture.php?albumid=1&pictureid=4)

Dave



Wow, real beauties! Those power numbers are beyond impressive.  Any chance for a "Son of Frankengun"?
Title: Re: realistic 2240 power expectations
Post by: Flyboy on June 26, 2013, 06:43:58 AM
So I guess with a HiPac conversion you can comfortably use a more powerful hammer spring as there's no valve pin having to ram into a CO2 cartridge and potentially get stuck? What relationship does the hammer even have with a HiPac after conversion? How does it all work exactly?

Another thing, what caliber and what grain of pellet are you guys using to get such high foot-poundage out of your guns? You know I used to think that FPE was the primary calculation of power in airguns, but have since come to think that in fact muzzle velocity and pellet grain are the primary factors, and FPE is kind of just like a by-product that is the result of those two properties working in cohesion.
Title: Re: realistic 2240 power expectations
Post by: grumpy on June 26, 2013, 09:39:53 AM
For all of my guns I keep caliber to .22. I know several who went as big as .25
Title: Re: realistic 2240 power expectations
Post by: AmBraCol on June 26, 2013, 10:18:06 AM
So I guess with a HiPac conversion you can comfortably use a more powerful hammer spring as there's no valve pin having to ram into a CO2 cartridge and potentially get stuck? What relationship does the hammer even have with a HiPac after conversion? How does it all work exactly?

Another thing, what caliber and what grain of pellet are you guys using to get such high foot-poundage out of your guns? You know I used to think that FPE was the primary calculation of power in airguns, but have since come to think that in fact muzzle velocity and pellet grain are the primary factors, and FPE is kind of just like a by-product that is the result of those two properties working in cohesion.

That's exactly what FPE is.  In my opinion, FPS is important.  Too low (like the Canadian limit of 500 fps) and you've got a rainbow trajectory that makes hitting way out there quite a feat. FPS at a reasonable level gives you a relatively flat shooting rifle that allows you to "reach out and touch something".  If you can keep the FPS up while launching a heavier pellet then you're also going to be able to touch something effectively.  There are those who favor light pellets to keep the FPS up to astonishing levels. But a light pellet won't carry as far as a heavy one since it doesn't have the mass to keep up the momentum,  This is why I'm fascinated with the Korean and Turkish guns.  They get high velocity out of regular pellets - and can get decent velocity out of cast projectiles.  This allows you to have a flat (relatively) trajectory while transmitting amazing power at the target.  FPE doesn't tell as much (to my mind) as FPS and pellet weight.  Theoretically you can drive a 7 grain pellet to 1,134.2 FPS and obtain 20 FPE.  1,035.37 fps will give you the same FPE from an 8.4 grain pellet. Now let's reach up a bit higher for 30 FPE and you'll drive the same 8.4 gr pellet to 1,268.07 and 1,389.1 with the 7 grain.  At those speeds you can pretty much kiss accuracy goodbye.  If you kick the pellet weight up to 15 grains, however, you only have to drive it to 948.94 to reach 30 FPE.  You've got the FPE while keeping your projectile within the generally accepted velocity for accuracy.  A Canadian would have to launch a 55 grain projectile at 495.57 to reach 30 FPE and stay under their 500 FPS velocity for a non PAL rifle.  Of course, the minute they test that rifle with a light pellet - he's busted for having an illegal weapon.


Title: Re: realistic 2240 power expectations
Post by: Flyboy on June 26, 2013, 10:43:22 AM
That's exactly what FPE is.  In my opinion, FPS is important.  Too low (like the Canadian limit of 500 fps) and you've got a rainbow trajectory that makes hitting way out there quite a feat. FPS at a reasonable level gives you a relatively flat shooting rifle that allows you to "reach out and touch something".  If you can keep the FPS up while launching a heavier pellet then you're also going to be able to touch something effectively.  There are those who favor light pellets to keep the FPS up to astonishing levels. But a light pellet won't carry as far as a heavy one since it doesn't have the mass to keep up the momentum,  This is why I'm fascinated with the Korean and Turkish guns.  They get high velocity out of regular pellets - and can get decent velocity out of cast projectiles.  This allows you to have a flat (relatively) trajectory while transmitting amazing power at the target.  FPE doesn't tell as much (to my mind) as FPS and pellet weight.  Theoretically you can drive a 7 grain pellet to 1,134.2 FPS and obtain 20 FPE.  1,035.37 fps will give you the same FPE from an 8.4 grain pellet. Now let's reach up a bit higher for 30 FPE and you'll drive the same 8.4 gr pellet to 1,268.07 and 1,389.1 with the 7 grain.  At those speeds you can pretty much kiss accuracy goodbye.  If you kick the pellet weight up to 15 grains, however, you only have to drive it to 948.94 to reach 30 FPE.  You've got the FPE while keeping your projectile within the generally accepted velocity for accuracy.  A Canadian would have to launch a 55 grain projectile at 495.57 to reach 30 FPE and stay under their 500 FPS velocity for a non PAL rifle.  Of course, the minute they test that rifle with a light pellet - he's busted for having an illegal weapon.

Here in the UK all air rifles are measured by ft. lbs. in power. But I have now come to treat any stated figures with caution, as it all depends on what pellet you are using. How can you honestly sell someone a 'legal power' air rifle that is 11.9 ft. lbs. in power (has to be below the actual number of 12), when they could so easily just use a higher grain pellet than whatever those stats were conjured up with, and take it to over the legal limit? At the same time, if you're using a lighter grain pellet, you could kick up a stink for not having anything near 11.9 ft. lbs.

It then gets even more confusing when they detail the power in Joules for replica CO2 pistols and FPS for airsoft guns... all the while being left open for question by the weight of the ammunition you use.
Title: Re: realistic 2240 power expectations
Post by: AmBraCol on June 26, 2013, 12:15:19 PM
That's exactly what FPE is.  In my opinion, FPS is important.  Too low (like the Canadian limit of 500 fps) and you've got a rainbow trajectory that makes hitting way out there quite a feat. FPS at a reasonable level gives you a relatively flat shooting rifle that allows you to "reach out and touch something".  If you can keep the FPS up while launching a heavier pellet then you're also going to be able to touch something effectively.  There are those who favor light pellets to keep the FPS up to astonishing levels. But a light pellet won't carry as far as a heavy one since it doesn't have the mass to keep up the momentum,  This is why I'm fascinated with the Korean and Turkish guns.  They get high velocity out of regular pellets - and can get decent velocity out of cast projectiles.  This allows you to have a flat (relatively) trajectory while transmitting amazing power at the target.  FPE doesn't tell as much (to my mind) as FPS and pellet weight.  Theoretically you can drive a 7 grain pellet to 1,134.2 FPS and obtain 20 FPE.  1,035.37 fps will give you the same FPE from an 8.4 grain pellet. Now let's reach up a bit higher for 30 FPE and you'll drive the same 8.4 gr pellet to 1,268.07 and 1,389.1 with the 7 grain.  At those speeds you can pretty much kiss accuracy goodbye.  If you kick the pellet weight up to 15 grains, however, you only have to drive it to 948.94 to reach 30 FPE.  You've got the FPE while keeping your projectile within the generally accepted velocity for accuracy.  A Canadian would have to launch a 55 grain projectile at 495.57 to reach 30 FPE and stay under their 500 FPS velocity for a non PAL rifle.  Of course, the minute they test that rifle with a light pellet - he's busted for having an illegal weapon.

Here in the UK all air rifles are measured by ft. lbs. in power. But I have now come to treat any stated figures with caution, as it all depends on what pellet you are using. How can you honestly sell someone a 'legal power' air rifle that is 11.9 ft. lbs. in power (has to be below the actual number of 12), when they could so easily just use a higher grain pellet than whatever those stats were conjured up with, and take it to over the legal limit? At the same time, if you're using a lighter grain pellet, you could kick up a stink for not having anything near 11.9 ft. lbs.

It then gets even more confusing when they detail the power in Joules for replica CO2 pistols and FPS for airsoft guns... all the while being left open for question by the weight of the ammunition you use.

SO far, we have no such limits.  The limits imposed are that we are no longer allowed to import anything without going through a license importer.  And they all jack prices up a HUGE percent.  A 2240 here, for example, runs about $150 US dollars, give or take.  That's only three times the US price, approximately.  Any shooting sport here is expensive, but air guns are still the affordable route compared to firearms. 
Title: Re: realistic 2240 power expectations
Post by: mtsheron70 on June 26, 2013, 01:46:03 PM
joklak-

I look to get a CC 2300KT and put in a Crooked Barn (Jim Giles) Boss Valve which according to Jim will give you 30% more power on average.  So if you take the claimed 460 fps and get 30% more you would be at 598 fps.  But I am sure that is with a light pellet.  I wish they would state the pellet weights used on these ratings.

So these numbers I am sure will vary.  But something to work with of course.
Title: Re: realistic 2240 power expectations
Post by: joklak on June 26, 2013, 02:18:44 PM
I appreciate all of the info.  I would like to stick with the 12 gram co2 because I am going to get a .25 marauder soon.  What I want to do is have a nice short gun for pest control that wont stick way out of the window for everyone to see. I also was hoping to get enough power to take head shots on racoons if I need to.  I guess if it dont work I will make a shooting stick so I dont have to put a longer gun out the window.
Title: Re: realistic 2240 power expectations
Post by: AmBraCol on June 26, 2013, 02:33:59 PM
I appreciate all of the info.  I would like to stick with the 12 gram co2 because I am going to get a .25 marauder soon.  What I want to do is have a nice short gun for pest control that wont stick way out of the window for everyone to see. I also was hoping to get enough power to take head shots on racoons if I need to.  I guess if it dont work I will make a shooting stick so I dont have to put a longer gun out the window.

A .25 Marauder would be preferable for head shots on coons.  You might be able to get the power of a 2240 up to where it would take a coon OK with the headshot, but it's going to take a lot more finesse on the part of the shooter.  If you can get up close then the pistol is fine and is more easily slipped under a jacket or other garment to prevent inquisitive eyes from seeing the tool.  If you're shooting out of a window there's a lot to be said for doing so with a long gun with a scope from back inside the room somewhere.  Plus, the Marauder will be much quieter than the 2240, especially if you pull away from the window - that way what sound IS emitted will be further dispersed prior to leaving the confines of the room you're shooting from.
Title: Re: realistic 2240 power expectations
Post by: joklak on June 26, 2013, 02:40:10 PM
I appreciate all of the info.  I would like to stick with the 12 gram co2 because I am going to get a .25 marauder soon.  What I want to do is have a nice short gun for pest control that wont stick way out of the window for everyone to see. I also was hoping to get enough power to take head shots on racoons if I need to.  I guess if it dont work I will make a shooting stick so I dont have to put a longer gun out the window.

A .25 Marauder would be preferable for head shots on coons.  You might be able to get the power of a 2240 up to where it would take a coon OK with the headshot, but it's going to take a lot more finesse on the part of the shooter.  If you can get up close then the pistol is fine and is more easily slipped under a jacket or other garment to prevent inquisitive eyes from seeing the tool.  If you're shooting out of a window there's a lot to be said for doing so with a long gun with a scope from back inside the room somewhere.  Plus, the Marauder will be much quieter than the 2240, especially if you pull away from the window - that way what sound IS emitted will be further dispersed prior to leaving the confines of the room you're shooting from.

I am in the process of making the 2240 a carbine so the barrel wont stick out to far and I have a tko muzzle brake which really helps a lot.  In a way I guess I just needed a project.
Title: Re: realistic 2240 power expectations
Post by: AmBraCol on June 26, 2013, 03:08:41 PM
I am in the process of making the 2240 a carbine so the barrel wont stick out to far and I have a tko muzzle brake which really helps a lot.  In a way I guess I just needed a project.

Sounds like a cool project. :)  Getting that barrel out there goes a long ways towards improving the velocity and therefore power of the piece.  I've run into the problem of sourcing parts/donor guns but have a couple similar projects in different stages of planning.
Title: Re: realistic 2240 power expectations
Post by: rsterne on June 27, 2013, 01:34:43 AM
cwlongshot.... My work on the .22 Disco was all done and documented before I joined the GTA, so I have nothing I can link you to.... Basically, I bored out the valve, enlarged and streamlined the ports, opened up the inlet and the gauge block so more air could get into the valve, ran a slightly heavier hammer spring, shortened the valve stem a bit to increase hammer travel, slimmed the stem and drilled out the throat to increase the throat area, etc,etc,etc.... and installed stronger valve screws.... I got 53 FPE peak with EunJins, 10 shots strings averaging 51 FPE from 2500 psi down to 1500.... I ended up detuning the gun to 36 FPE and using 18 gr. JSB Heavies as they were the most accurate at about 950 fps, and better than any other pellet for accuracy at long range....

Power is fun, but accuracy is where it's at.... I run all my .22 cal PCPs at around 36 FPE....

Bob
Title: Re: realistic 2240 power expectations
Post by: cwlongshot on June 27, 2013, 06:43:31 AM
cwlongshot.... My work on the .22 Disco was all done and documented before I joined the GTA, so I have nothing I can link you to.... Basically, I bored out the valve, enlarged and streamlined the ports, opened up the inlet and the gauge block so more air could get into the valve, ran a slightly heavier hammer spring, shortened the valve stem a bit to increase hammer travel, slimmed the stem and drilled out the throat to increase the throat area, etc,etc,etc.... and installed stronger valve screws.... I got 53 FPE peak with EunJins, 10 shots strings averaging 51 FPE from 2500 psi down to 1500.... I ended up detuning the gun to 36 FPE and using 18 gr. JSB Heavies as they were the most accurate at about 950 fps, and better than any other pellet for accuracy at long range....

Power is fun, but accuracy is where it's at.... I run all my .22 cal PCPs at around 36 FPE....

Bob

Thanks Bob.

I'll be contacting you when I make the step.  ::)  As I said, Making my Disco a 30-35 fpe gun is my target.  (Once I buy one)  ;)

CW
Title: Re: realistic 2240 power expectations
Post by: silent_airman on June 27, 2013, 08:17:11 AM
cwlongshot.... My work on the .22 Disco was all done and documented before I joined the GTA, so I have nothing I can link you to.... Basically, I bored out the valve, enlarged and streamlined the ports, opened up the inlet and the gauge block so more air could get into the valve, ran a slightly heavier hammer spring, shortened the valve stem a bit to increase hammer travel, slimmed the stem and drilled out the throat to increase the throat area, etc,etc,etc.... and installed stronger valve screws.... I got 53 FPE peak with EunJins, 10 shots strings averaging 51 FPE from 2500 psi down to 1500.... I ended up detuning the gun to 36 FPE and using 18 gr. JSB Heavies as they were the most accurate at about 950 fps, and better than any other pellet for accuracy at long range....

Power is fun, but accuracy is where it's at.... I run all my .22 cal PCPs at around 36 FPE....

Bob

I have one question. Where and how did you learn all that? It's all Greek to me, but i would love to learn. I also imagine you have to have some decent shop tools. So far I can change barrels, play around with triggers, and mount scopes. Pretty basic stuff but I would like to go deeper. Any suggestions?
Title: Re: realistic 2240 power expectations
Post by: Flyboy on June 27, 2013, 09:55:10 AM
I have one question. Where and how did you learn all that? It's all Greek to me, but i would love to learn. I also imagine you have to have some decent shop tools. So far I can change barrels, play around with triggers, and mount scopes. Pretty basic stuff but I would like to go deeper. Any suggestions?

I've literally only had a 2250B for a month today, have already been modding it for the last couple of weeks and have already completely disassembled the gun. So far I have added/replaced a steel breech, power adjuster, re-bolt kit, trigger kit, safety bar, hammer spring and seal. As well as mounting a Red Dot sight and sound mod.

These guns are really so simple it's hard to go wrong. In most situations it's just a case of remove the old part, replace with new part. YouTube also has some good videos on fitting various parts and also complete disassembly/assembly if you get stuck.
Title: Re: realistic 2240 power expectations
Post by: joklak on June 27, 2013, 11:37:37 PM
cwlongshot.... My work on the .22 Disco was all done and documented before I joined the GTA, so I have nothing I can link you to.... Basically, I bored out the valve, enlarged and streamlined the ports, opened up the inlet and the gauge block so more air could get into the valve, ran a slightly heavier hammer spring, shortened the valve stem a bit to increase hammer travel, slimmed the stem and drilled out the throat to increase the throat area, etc,etc,etc.... and installed stronger valve screws.... I got 53 FPE peak with EunJins, 10 shots strings averaging 51 FPE from 2500 psi down to 1500.... I ended up detuning the gun to 36 FPE and using 18 gr. JSB Heavies as they were the most accurate at about 950 fps, and better than any other pellet for accuracy at long range....

Power is fun, but accuracy is where it's at.... I run all my .22 cal PCPs at around 36 FPE....

Bob

Sounds like a pretty awsome project.  I saw over in the pcp gate you are modding a disco to .30cal and it seems like something I may like to do in the future.  Do you have use a totally different valve or anything to get it to run above 2000psi?
Title: Re: realistic 2240 power expectations
Post by: RScott on December 21, 2020, 09:56:33 AM
RSterne posted on Re: realistic 2240 power expectations
« Reply #9 on: June 24, 2013, 06:34:28 PM »
Quote
The biggest limit with a 2240 is barrel length, the second biggest limit is CO2.... Put a 24" barrel on it, a few mods, run it on HPA, and it becomes a Disco.... I have modded a Disco to 53 FPE in .22 cal, over 100 FPE in .25 cal, and 133 FPE in 9mm.... If you're talking a shorter barrel and leaving it on CO2, then give your head a shake, it ain't gonna happen....

Mr. Stern,
In other postings, your graphs indicate the potential to get to about 22 fpe with a CO2 powered gun with a transfer port of about 0.154 inches.  I have that port size, a max boss valve, stronger hammer trigger, hollow/extended probe, an 18 inch barrel, and use bulk CO2 from a 9 ounce tank.  With 14.3 grain CP hollow point pellets I get 570 fps = 10.3 fpe.  My max fpe comes with 34 grain JSB Beasts: 428 fps gives 13.8 fpe.  Some of those pellets don't allow me to close the bolt so I also use Skenco Newboy Heavy Weights for similar results.
But 13.8 fpe is far below my 22 fpe target.  What do you think is holding me back?  Should I use a longer barrel?  My configuration uses about 0.75 grams of CO2 per shot but I don't know if I am wasting gas or not.  (I use a Silent Thunder Falx moderator and get about 80db 3 feet perpendicular to the muzzle).  I don't know where in the barrel the pellet is when the valve closes.
Regards.   

Title: Re: realistic 2240 power expectations
Post by: fivestar45 on December 21, 2020, 04:06:37 PM
I think there's something missing in your combination. I've had a few 22xx's bulk filled, 18" barrel and probably a smaller valve volume and my results @ 70 deg's F were always in the 750's with 14.3 pellets.
Title: Re: realistic 2240 power expectations
Post by: RScott on December 21, 2020, 05:08:44 PM
fivestar45:

Thanks for the response.  Yes, your 750 fps is much higher than mine, and you are getting about 18 fpe, with your medium weight pellets.  With all of my mods (described in prior post), I get only 675 FPS with 9.56 grain pellets (H&N Field Target Trophy Green).
I guess I'll play around with hammer spring pressure.  Currently I use the one that came with the max boss valve (from AlchemyAirWerks), but he also sent me a hammer spring adjuster kit.

I hope to hear from Bob Stern about this too.
Title: Re: realistic 2240 power expectations
Post by: fivestar45 on December 21, 2020, 09:04:04 PM
Are you using a drop block with a 9oz tank? What length tube? Did you open the barrel port?
Also sear drag could be a killer of your speed. Another thing, using co2 I haven't found that I need any stronger spring than what is used OEM Crosman 1322. And I generally use a lightened striker.
Title: Re: realistic 2240 power expectations
Post by: RScott on December 21, 2020, 09:41:47 PM
fivestar45:

No drop block.  I use a Ninja coiled tube adapter that stretches out to about 55 inches.  During my FPS tests, the 9 oz CO2 bottle sits upright or at a slight angle from upright and the top of the bottle is a few inches below the powerlet eliminator on the 2240.  The coil droops down then up from the CO2 bottle's valve to the gun.  (When I am cane toad hunting - the main use of my gun - the bottle is in my pants pocket and is about one foot below the gun.)

I use a Alliance Hobby wide diameter transfer port.  I think it is about 0.154 inches diameter; definitely wider than the OEM port.  I did not modify the barrel itself.  The max boss valve has an angled exit port.  I confirmed that the hollow bolt has its entry hole on the bottom, i.e., aligned with the transfer port.

Do you have an estimate of CO2 consumption per shot in your high FPS configuration, e.g., how many shots would you get from a 12 gram powerlet?  I estimate 0.75 grams per shot from my bulk CO2 set up based on cylinder weight before and after shooting 75 rounds and adjusting for CO2 consumed/lost in the bulk adapter line.  Perhaps I am not moving enough CO2 per shot.  Or maybe I am moving enough but the flow rate is constrained.

Thanks for the ideas.
Title: Re: realistic 2240 power expectations
Post by: rsterne on December 21, 2020, 11:51:18 PM
I don't know what thread you are referring to, but my guess is that the barrel length and/or caliber is wayyyyyyyyyyyy more than a 2240.... I have a .30 cal pistol running on CO2, with a 12.5" barrel, that shoots just under 500 fps with a 45 gr. pellet.... That's about 25 FPE....

Bob
Title: Re: realistic 2240 power expectations
Post by: RScott on December 22, 2020, 12:21:22 AM
Here is the chart from a 2013 rsterne post that I looked at and thought I could achieve 22 fpe with my CO2-powered 2240 modified for high flow (as described in a prior post), including a 0.154 inch diameter transfer port.  But as described before, I am not coming close, even with 34 grain .22 pellets.  fivestar45's comments have me thinking I need to run experiments with hammer spring tension.  Also I don't know if the roughly 0.75 grams of CO2 per shot is enough or overkill for boosting fps and fpe in my 18" barrel length gun.

Or have I badly misinterpreted your graph of potential fpe for a .22 caliber CO2 gun?

Thanks.

Title: Re: realistic 2240 power expectations
Post by: Tack Driver 10 on December 22, 2020, 09:14:11 AM
I modded a 2400KT CSS gun a few years back.
The max I was able to coax out of it with an 18" barrel was 660 FPS, 13.85 FPE with 14.3 CPHPs.

With a 22 3/4" barrel made 706 FPS, 15.82 FPE with 14.3 CPHPs.
Max was 505 FPS,19.23 FPE with 33.94 Beast pellets.
Title: Re: realistic 2240 power expectations
Post by: RScott on December 22, 2020, 10:24:15 AM
TD10:
Your data is very interesting and helpful.

- Very interesting because you got the often quoted "10 fps increase per inch of barrel length" result for extending your barrel beyond 18 inches.  I had assumed that beyond 18" the rate of increase in speed would be much lower.  But maybe the larger valve volume and port diameter result in higher and faster flow.  That I still get an 80db retort at the muzzle suggests a bunch of CO2 is still flowing fast with my 18".  Previous posts/analyses have suggested speed can increase until the barrel length is well above 35", when at some point friction offsets gas pressure.  I can't increase my barrel length and have the gun be practical for walking golf courses at night to shoot cane toads.  But this is great to know in case I use the gun for just backyard iguanas.

- Very helpful because you got 660 fps with CPHPs going through your 18" barrel and I'm at only 570 fps with those.  I'll start playing around with hammer spring strength and maybe the inner valve spring.  Then all the other possibilities that fivestar45 raised.

Thanks very much.
RScott

P.S. for rsterne:
- In a prior post I attached a graph from an 2013 post of yours indicating max potential 22 fpe with unconstrained CO2 .22 with 0.154 inch diameter transfer port.  Looking at the graph for .30 caliber, the max fpe with that same size port was about 35 fpe with a 0.154 transfer port or about 45 fpe with a 0.21 transfer port (i.e., roughly 70% of caliber/barrel diameter).  Your quoted 25 fpe suggests your experience is well below that max.  Maybe due to the relatively short barrel length?
Title: Re: realistic 2240 power expectations
Post by: RScott on December 22, 2020, 10:39:14 AM
To minimize the extent to which I get rstern perturbed, I need to attach his disclaimer to the charts I referred to (that suggested a max 22 fpe for my gun configuration).  These are from a 2013 post of many graphs by him:

The port sizes are in 1/64ths of an inch increments up to .35 cal, starting from 1/16".... Above that, the increments are 1/32", with the minimum port diamter increasing gradually.... In every case, the maximum port size is the closest drill size to the full caliber diameter.... I'm not aware of any .22 cal or smaller airguns that use 4500 psi for a fill pressure, so the graphs don't show that.... The 850 psi lines shown are for HPA, it is unlikely that CO2 could achieve the FPE levels shown because of the increased density drag of the heavier CO2.... This is not because of the pressure, but rather a decrease in efficiency due to friction, IMO....
NOTE: I am not claiming that the above graphs are accurate, or achievable.... I am offering them as a point of discussion to further develop the possibility of being able to predict how big the ports need to be in a PCP to develop a given FPE with a given pressure.... I am particularly interested, currently, in how increasing the caliber effects the FPE without any other changes to the gun, other than an adjustment in the hammer strike to allow more dwell to allow the same valve closure point in the larger volume barrel.... The first practical test will hopefully be in my next project, a .30 cal Disco Double which will also have a .25 cal barrel option.... The plan is to use a 3/16" (0.188") port straight through, and at 2000 psi that predicts 74 FPE in .25 cal and 88 FPE in .30 cal.... I am going to set those as my (rather lofty) goals for this project and see what happens....
Bob


I could not find his actual results to compare to the theoretical maximums.
But I had previously overlooked his caution that "the 850 psi lines are for HPA; it is unlikely that CO2 could achieve the FPE levels shown because of the increased drag of the heavier CO2". . .  great clarification that I had missed.

Regards,
RScott
Title: Re: realistic 2240 power expectations
Post by: rsterne on December 22, 2020, 02:47:15 PM
Quote
P.S. for rsterne:
- In a prior post I attached a graph from an 2013 post of yours indicating max potential 22 fpe with unconstrained CO2 .22 with 0.154 inch diameter transfer port.  Looking at the graph for .30 caliber, the max fpe with that same size port was about 35 fpe with a 0.154 transfer port or about 45 fpe with a 0.21 transfer port (i.e., roughly 70% of caliber/barrel diameter).  Your quoted 25 fpe suggests your experience is well below that max.  Maybe due to the relatively short barrel length?

Simply using a chart you find, without checking into the criteria used to develop it, can definitely lead to disappointment.... The  thread from 2013, containing those charts, can be found at....

https://www.gatewaytoairguns.org/GTA/index.php?topic=46011. (https://www.gatewaytoairguns.org/GTA/index.php?topic=46011.)

You need to read carefully the first post in that thread to understand where the charts came from.... I explained that the chart in the first post represented the theoretical maximum FPE per foot of barrel length, assuming 100% efficiency.... There are many losses in an actual PCP.... The mass of the gas itself is one of the largest ones, and the pressure is not a constant, it always falls during the shot.... There are frictional losses, and losses if the ports are not bore-sized.... Note that for a .22 cal with a 12" barrel at 850 psi, the theoretical maximum FPE is 32 FPE....  :o .... In practice, you would be lucky to achieve that with a 24" barrel, as mentioned in that first post....

The charts in the second post take into account the reduction of FPE caused by restricting the port size.... Instead of using the bore area, I used the product of the caliber and the port diameter.... then multiply that by the pressure.... Note in that post the words....

Quote
Potential FPE = Force x 1 Foot

Since we are lucky to get that force equivalent in a 24" barrel, that length should be assumed for all those charts.... I have added that correction in RED to make that clearer.... My "lofty goal" formula, in its current form, is as follows....

FPE Goal = (Caliber x Port Diam. x PI/4) x Pressure x (Barrel length / 24).... which can also be written = Barrel Volume (cu.in) x Pressure / 24....

For a .22 cal with a 0.154" port and a 24" barrel running at 850 psi, we get....

(.22 x .154 x 3.1416 / 4) x 850 x 24 / 24 = (0.0266 x 850) x 1 = 22.6 FPE.... For a 12" barrel, the lofty goal would be half that....  ;)

Note that my "lofty goal" is not easy to achieve.... I have never managed to do it with a projectile weight of half the FPE goal (ie at 950 fps).... I can get about 90% when set to maximum power.... but to get to the goal I always need more pressure, a longer barrel, or a heavier projectile.... If you can reach the "lofty goal" as calculated above, you have done an exceptional job.... Using CO2 it would be even more difficult, as that gas is 58% heavier than air.... and hence a larger percentage of the available FPE goes into propelling it, reducing the efficiency even lower....

I hope that answers your questions....

Bob
Title: Re: realistic 2240 power expectations
Post by: RScott on December 22, 2020, 03:42:21 PM
Bob,
Thank you for the detailed reaction and guidance to my questions.  You've helped me appreciate how to frame the 22-23 fpe goal I interpreted from your prior work.
Your comments make the achievement described by Tack Driver 10 even more impressive.  He got to 19 fpe with heavy pellets in a 22.75 inch barrel in his 2400KT.  That is close to 90% of the max for that barrel length.
I'll experiment with hammer and valve springs to see what optimum I can achieve with fairly heavy pellets.  I'd like to use my gun to humanely dispatch iguanas at about 30-40 yards and have felt the need to max the muzzle power and pellet speed to accomplish this.

I'm still working on figuring out where along the barrel the pellet is when the valve closes.  You have some posts on this in 2017 I'll study.

As a newbie to air guns, and as chemical engineer who hasn't done that type of work for several decades, I find this stuff fascinating.
Title: Re: realistic 2240 power expectations
Post by: RScott on December 22, 2020, 04:46:08 PM
fivestar 45 wrote:
Hi I tried to reply to your posts twice today however they didn't show.
What you are using for power is "Bulk Feed" not "Bulk Fill" this in itself, the way you are doing it will keep you from much of a gain in performance. Your T/P configuration is another problem..large T/P feeding a small barrel port = no more flow than the small barrel port.
The valve, does it have a piercing pin? as would be used with a standard 2240 that uses 12g's for power?
The best performance from co2 comes from a bulk filled tube, or an unrestricted bottle fed tube with plenum space. Coil lines, especially long ones feeding through 12g eliminators will  give little if any performance increase over 12g's they will only add shot count.

RScott replied:
Interesting.  Sounds like there can be a lot of pressure drop from the long distance and narrow tubing from the 9 oz bottle to the valve.  I understand from your note that a large plenum near the valve would overcome this problem?  But that requires a very different configuration than the simple powerlet eliminator I use, i.e., the tube itself would have to be pressurized which would require sealing around the valve, or installing a very wide powerlet eliminator (i.e., basically a powerlet connected to a bulk tank).

Currently I still have the piercing pin on my valve but I've thought about removing it in case it was prematurely cutting off or slowing flow to the valve.  I assume removing it would not cause leaks through the valve, i.e., the valve's internal seal must be preventing leakage to the transfer port, right?

By "bulk fill", do you mean getting the CO2 in liquid form to the valve?  If so, could I position the 9 oz tank in an upside down position above the tube and valve assembly?  I've wondered what problems/risks that would cause?  But in theory I'd be getting liquid CO2 along the flex tubing and into the powerlet eliminator, and the 9 oz tank would have a CO2 gas head above its liquid level and feed liquid CO2 through its valve.

My amazement at the expertise and precision of the folks on this site continues to grow.
Title: Re: realistic 2240 power expectations
Post by: Tack Driver 10 on December 22, 2020, 05:09:36 PM
RScott,

Here's a link to my 2400KT build.
Used several different barrels etc so should give you some good base info.

https://www.gatewaytoairguns.org/GTA/index.php?topic=146205.0 (https://www.gatewaytoairguns.org/GTA/index.php?topic=146205.0)
Title: Re: realistic 2240 power expectations
Post by: RScott on December 22, 2020, 06:43:13 PM
TD10:
- Wow.  That is an impressive set of modifications.  And your gun is gorgeous.
- I came to understand from your link and fivestar45's posts that I've been looking at only the transfer port diameter and missing the barrel port width.  I checked my 2240's original 7.5" barrel and the narrow part of its port appears to be only 0.13 inches.  Cripe!  I'll look at the 18" barrel and will drill it out to at least the .166 you described.
Title: Re: realistic 2240 power expectations
Post by: RScott on December 22, 2020, 07:08:52 PM
fivestar45 wrote:
So far you have accumulated several parts that will yield very little performance increase.

Bulk Fill usually is regarded as filling the tube with liquid co2. The + is the higher the capacity the tube, the longer it takes to chill in use and produces a more consistent shot to shot speed.
The piercing pin stem has soft seating material it is slow responding and hampers performance. Get a stem for a Discovery, no piercing pin and harder seating material it responds quicker.
Pressurizing the tube is the easy part, doing it safely takes a bit more. But the result is worth it.
You are fortunate to live in a part of the U.S. that the temperature range will give good co2 performance most of the time.

RScott writes:
- I've ordered the Discovery stem and will try it when it arrives next week, along with a drilled out barrel port as you and Tack Driver 10 suggested
- Can you point me to a source of high capacity tubes or other configurations that will safely hold liquid CO2 and make sure the tube is filled with liquid?
- Yes, we are in SWFL.  Today is chilly with a high in the low 70's and low in the upper 50's.  I got into pellet guns this past Spring when I realized it was the most fun way to take out invasive cane toads.  Most of our local volunteer toad removers pick them up and freeze them.  Shots to the back of the neck seem much more humane, and are vastly more fun, particularly when shooting from about 10-15 feet away.  But I'm now wanting to up the fpes so I can humanely kill iguanas, which requires accurate 30-40 yard shots around here.  And I'm hoping the higher fpes will instantly kill the toads when shots are slightly off-the-mark.   Modding the 2240 has been a blast in my quest to achieve this.  I've scoured the forums to learn from others.  And I'm humbled to be getting direct guidance from you, rsterne, and Tack Driver 10.  But I'm starting to think I'll end up getting a PCP to ensure enough fpes at the target.