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PostPosted: Thu Mar 09, 2017 11:22 am 
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Location: Caronport, Saskatchewan
Well, I got this thing working! I drilled and tapped a 1/8npt hole through the side of my pump tube and valve and connected an ASA with pressure gauge to it. Then I put a spent 88g co2 cartridge with Asa adapter on it. I drilled a hole in the hammer end cap and threaded a small bolt in and put a spring guide/cap on the hammer spring (changed to a valve spring to keep legal fps) in order to have a velocity adjuster. With only a few turns in on the adjuster and the bottle only pumped up to around 750-800 psi I was able to get 21 shots starting at 493fps down to 467. Pretty good I think! The 22nd shot was 432fps. It took a 100 pumps to get the pressure back up. I'll have to try it at 1200psi (my one fitting is only rated for 1200psi) and turn the adjuster out a bit and see how it does. I'm pretty happy though with it now as it isn't very hard pumping. Oh yeah and my pump rubber end is a little damaged from a leaking valve earlier in the process so once I get the new one in the mail hopefully it'll be a few less pumps!
Still 22 shots for a 100 pumps is pretty great! I had drilled and tapped a one way foster valve in the end of the 88g co2 but I see now I didn't need to.
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Here is my shot string: (starting around 775psi, and using various benjamin 14.3 grain pellets , so my apologies for the random pellets)
1. 493
2. 487
3. 490
4. 488
5. 480
6. 480
7. 488
8. 480
9. 480
10. 483
11. 483
12. 477
13. 481
14. 481
15. 481
16. Didn't register
17. 471
18. 476
19. 471
20. 465
21. 467
22. 432

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PostPosted: Thu Mar 09, 2017 11:34 am 
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Nice work.


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PostPosted: Thu Mar 09, 2017 12:04 pm 
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Thanks!
I suppose if a person wanted to make sure it couldn't easily be adjusted to shoot past legal limits I would have to put a 1000 psi burst disk somewhere and take the adjuster off and attach some washers on the end of the hammer spring at just the right tension. Then it won't be easily adjusted by any officer checking it out to shoot over 500 fps. I would like to take this out hunting grouse or rabbits sometime, see how it does. Pretty accurate with the scope, shooting at 30 yards with a bit of wind, still breaks the daisy red disks every time :) .

I should probably secure the bottom end of the cartridge to the gun as well, to make sure the fitting doesn't turn and break the seal on the threads. :?

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PostPosted: Thu Mar 09, 2017 12:30 pm 
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Location: Bradford
I wouldn't have thought of that in 300 years, what a neat idea and obviously nice skills to make the idea into reality.

So....if one didn't mind the cost of the 88g or 90g CO2 cartridges, something like that may work on a 2240?...I've got a couple laying around, one all dolled up with the Crosman steel breech and other spiffy parts.

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PostPosted: Thu Mar 09, 2017 12:41 pm 
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You wouldn't have room in the 2240 valve, I don't think, to tap the hole through the side of it, but if you cut your 2240 tube just in front of the valve and then tapped the 1/8 npt thread through the front end of the valve and put an 90 degree fitting into it and attached your asa to that, it should work nicely. You'd have the cartridge running along under the barrel then and can use it as a forestock. I think that would look pretty good. Scopes and ammo has the cartridge and asa adapter as a kit, for pretty cheap I think, or you could buy the 88g adapter on its own from canadian tire for $9 and buy a pack of cartridges there. If you have a hpa hand pump you could put a fitting in the end of a used cartridge like I did and refill them for free. Just make sure not to fill past the 1800 psi safe limit for the cartridge. :)

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PostPosted: Thu Mar 09, 2017 12:44 pm 
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Bob Sterne has a picture of a 2240 valve with a fitting threaded into the end on one of the active threads here just recently. I think it is someone asking about modifying the 2240 to a pcp or hpa.

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PostPosted: Thu Mar 09, 2017 12:51 pm 
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ITGUY wrote:
I wouldn't have thought of that in 300 years, what a neat idea and obviously nice skills to make the idea into reality.

So....if one didn't mind the cost of the 88g or 90g CO2 cartridges, something like that may work on a 2240?...I've got a couple laying around, one all dolled up with the Crosman steel breech and other spiffy parts.


2240 valve is bigger dia then a 13xx tube.


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PostPosted: Thu Mar 09, 2017 1:06 pm 
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ITGUY wrote:
I wouldn't have thought of that in 300 years, what a neat idea and obviously nice skills to make the idea into reality.

So....if one didn't mind the cost of the 88g or 90g CO2 cartridges, something like that may work on a 2240?...I've got a couple laying around, one all dolled up with the Crosman steel breech and other spiffy parts.

I should give credit where it's due, though Bob probably wouldn't want to be associated with my amateur workmanship, it's his uber pumper and a few other's ideas that helped me get the courage to try it out. Bob did a fantastic job using a 2100 tube and a 16g cartridge and made a real power pumper that didn't take many pumps to fill. Mine is a less extensive version with a more unsightly tank exposed. His was hidden in the forestock when closed. I'm really happy with the shot count on mine though and the amount of pumps needed. [emoji4]

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PostPosted: Thu Mar 09, 2017 1:07 pm 
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Sorry Bob Sterne is who I was speaking of [emoji4]

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PostPosted: Thu Mar 09, 2017 4:31 pm 
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At lunch time I quickly pumped up the gun with my hand pump to 1200psi. I found that I actually had to increase the tension on the hammer spring to get similar fps, which makes sense because the poppet has more pressure keeping it closed. Never had time to shoot more than a few shots. Will have to test further. Interesting to see where the most efficient pumps per shots psi level will be. I'm thinking that keeping it at the lower level will be the most efficient as it seems to take more and more pumps to make a difference in pressure the higher the pressure already is.
Also if I adjust the velocity to 480 fps at 1200psi I'm thinking it will be going over the legal limit as the pressure starts to drop which is another problem.
I'm guessing maybe the 900-1000psi will probably be the max efficiency I'll get, looking forward to more testing! [emoji4]

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PostPosted: Thu Mar 09, 2017 4:34 pm 
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Has anyone else on here tried using a larger cartridge such as the 88g and kept the pump mechanism to fill it? If so what did you find most efficient?

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PostPosted: Thu Mar 09, 2017 8:43 pm 
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Well I tried it at 1000psi and got 26 shots too get back to the 750 or so psi I had started at before so I still had another 20 shots left when I quit that round. My fps started out at 478 and ended at 494. Most of the shots were in the high 480s and 90s with one going to 500 plus 2 unfortunately.
I then decided to pump it back to 100psi with the forearm pump and see how many pumps it would take (my last pump up to 1000 had been with the hand pump). It took 250 pumps to go from 750 to 1000! That is a lot of pumping! I then shot it back down to see how many shots I could get in the 500 to 450 range.
1st shot 474fps, 30th 480fps, 40th 466, 46th 452fps and 51 443fps. I still had 500 psi left at this point and easily could have gotten another 10 shots with higher fps by turning the velocity adjuster in a bit but I stopped there.

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PostPosted: Thu Mar 09, 2017 8:44 pm 
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(Oops I meant I pumped it back to 1000psi not 100[emoji51]!)

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PostPosted: Thu Mar 09, 2017 8:51 pm 
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I think the lesson is that unless a person has a hand pump to fill the tank before going hunting, setting it as I had the adjuster before and gun pumping it the 100 pumps to 750 psi is the most practical. 20 good shots is usually all a guy would need for a day grouse hunting, and if it's a good day and you're a terrible shot then it's only 100 more pumps to be back at it, lol [emoji4]

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PostPosted: Fri Mar 10, 2017 2:34 pm 
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Awesome project! Thanks for sharing!


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