fps lost per inch of barrel reduction?

[Steveoo]

MBowler….you are correct in respect of shorter barrel imparting less friction but the expansion of gas, or air in the pneumatic/ Co2 gun far outweighs this….

In the springer, there is little in the way of gas expansion….so not much to be gained above 10 inches or so..

 

[mrbowler1]

Thanks for the replies. I will look for that book. I do find the topic interesting. 

So in terms of "gas expansion" from a PCP or CO2 Gun I am trying to figure that one out. My original assumption was that a pulse of air was the same whether from a springer or PCP; however, apparently that is not the case. Is there an expansion / thermodynamic effect with a PCP since the air has been held under high pressure and suddenly been released as opposed to a springer that compresses the air upon release of the sear?

Matt

 

[mrbowler1]

As a follow-on to that note.....so with a springer the air is going from uncompressed to compressed and doing so over the period of time during which the piston moves forward (spread out over a few microseconds). With a PCP you have air going from a high pressure state to a maybe lower pressure state as it is instantaneously released...???