Gas piston affect on swept volume
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Gas piston affect on swept volume
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Topic: Gas piston affect on swept volume (Read 1255 times))
LaCombreKnives
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Posts: 11
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Real Name: Timothy
Gas piston affect on swept volume
«
on:
September 19, 2017, 01:53:28 PM »
Evening
Did a search but didn't come up with anything.
Does any one know how a gas piston affects swept volume compared to a spring? Like a formula or anything.
Example: I have a air rile with 55cc swept volume and with a spring I get lets say 650 FPS with a 14.5 gr pellet. Is there way to calculate what possible FPS could be achieved with same pellets with a 450 newton, then a 750 newton and then a 1250 newton gas spring without having to assemble and test fire all three?
I would assume that the gas spring would compress and push the air faster than a spring?
Thanks
Tim
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AmBraCol
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Re: Gas piston affect on swept volume
«
Reply #1 on:
September 19, 2017, 03:15:33 PM »
Swept volume is the volume of the chamber in front of the piston. The only way the nitro piston would change the swept volume would be if it were shorter or longer than the spring when compressed - and that is not likely to change as if it's too long or too short it will not allow the sear to engage.
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rsterne
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Re: Gas piston affect on swept volume
«
Reply #2 on:
September 19, 2017, 07:39:29 PM »
I am not aware of any formula THAT WORKS to tell you what velocity to expect with a given force of gas spring.... I can tell you, however, that using one that is too strong won't increase the velocity much, but it will nearly tear the gun out of your hands with the reverse recoil as the piston crashes into the front of the compression chamber.... IMO gas springs are highly over-rated, they are harder to cock at the beginning of the stroke for the same power (because they develop nearly the same force throughout their stroke).... and they can be VERY rough on scopes, particularly in the high powered springers....
Bob
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Re: Gas piston affect on swept volume
«
Reply #3 on:
September 19, 2017, 08:10:28 PM »
x2
We need to have a compulation of all of Bob's post in GTA maybe call it "the book of rsterne"
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LaCombreKnives
Shooter
Posts: 11
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Real Name: Timothy
Re: Gas piston affect on swept volume
«
Reply #4 on:
September 20, 2017, 12:18:11 AM »
Thanks all. I tend to agree. Was just curious about it. Did some tests with one in a slavia 630 that had no internal parts. Tore the rifle apart and split the stock in half. Fixed the stock, shortened the shaft on the gas piston until I only had 2mm pre load and she still shot like a mule. Then I shortened the shaft again so no pre load, just a snug fit and she shoots beautifully with hardly any recoil. Will do a chrono test when I have a chance.
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Gas piston affect on swept volume