GTA
All Springer/NP/PCP Air Gun Discussion General => Air Gun Gate => Topic started by: jim p on February 05, 2017, 10:21:32 PM
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I haven't really thought about this so don't laugh. Would it be possible to make a pump gun that would reach the pressure of a PCP? I am guessing that you would need enough stroke on the pump to reach the pressure desired. You would also need a small diameter pump piston so that you could apply enough force to complete the pump cycle. I guess that the biggest disadvantage would be having to make many pumps for each shot.
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FX Independence. On board pump pcp.
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I have been looking at some videos of the fx independence and it is very impressive.
I am afraid to look at the price but my next step is to look at the cost.
Thanks for pointing this rifle out to me.
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I just checked the price. So it looks like I will be shooting my 1377 for a while longer. :)
That gun does have a lot to offer.
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I haven't really thought about this so don't laugh. Would it be possible to make a pump gun that would reach the pressure of a PCP? I am guessing that you would need enough stroke on the pump to reach the pressure desired. You would also need a small diameter pump piston so that you could apply enough force to complete the pump cycle. I guess that the biggest disadvantage would be having to make many pumps for each shot.
It may be possible, but I feel like pumpers are what they are for a reason.
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http://www.gatewaytoairguns.org/GTA/index.php?topic=77463.0 (http://www.gatewaytoairguns.org/GTA/index.php?topic=77463.0)
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Yep, the rsterne subject above. I have a 1322C FTP carbine than I pinned after reading those tests.
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Thanks for linking that post about the piston modifications.
How hard is it to pump up to 15 pumps and what kind of speeds and fpe are you getting from the 1322?
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It's definitely possible, but at the end of the day it's a matter of energy.
When you're using a hand pump, you're using your whole body to compress the air. With a built in pump on a gun, you would be using only one arm, maybe both depending on your definition. So you'd either spend forever pumping, with relatively easy pumps, or it would be quite the workout, but not require that many pumps.
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Pumping the 1322 gets much more difficult up around 20 pumps for sure, but it is smooth. Right now it is retaining air after 16 pumps. I have not found the right spring yet; I just ordered a Discovery spring - I wanted a Maximus spring but Crosman cannot or will not deliver the latter for one year after being on the market. Taking a second shot at 25 pumps and adding the two shots together shows about 12 fpe. I don't know if that is a valid calculation but it seems it would be close to correct. Only getting 570 fps on the first shot at 25 pumps with a CPP 14.3 grain. But I am at 5835 feet in elevation.
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All the handpumps out there used to charge a PCP rifles use multiple stages, just like a regular HP Air Compressor. Your standard pumper airguns use a single stage.
There could be gains from using a larger bore for more air compressed per pump, but that also means hitting the "wall" faster- the point at which pumping becomes a bear. Another options would be increasing leverage- such as the Benjamin 39x PA "pump assist"- but those only make pumping easier. Then there's multi-stage pumpers such as the Indy and Independence (bullpup and rifle) by FX.
I'd like to see a 2-stage pumper using a a 3cm or maybe 1 1/4" ID bore for the LP stage and a smaller one for the HP stage, but it wouldn't be cheap, and as evidenced by the Millenium PUmper project, it probably wouldn't have many buyers.
Webley had a 4-pump pumper, that delivered some power, but IIRC it was plagued with reliability problems and quality control issues. So in the end, if you want a .22 pumper, the options are "roll your own" or go with either the 392 or the 1322. Of course, given that many Crosman parts are like Lego, building something that works good for you shouldn't be a major drain on the wallet to get a basic shooter.
Otherwise, best bet is a "remote pumper", meaning a PCP you fill with a handpump.
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i pumped a daisy 880 to 2000 psi fairly easy,,
http://www.gatewaytoairguns.org/GTA/index.php?topic=113523.0 (http://www.gatewaytoairguns.org/GTA/index.php?topic=113523.0)
on the green , a 2 stage pumper was pumped to 6000psi
http://www.network54.com/Forum/275684/message/1255819561/telescoping+piston+pics (http://www.network54.com/Forum/275684/message/1255819561/telescoping+piston+pics)
he used 2 stage , very easy also