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Crosman 2240 8 fpe

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TheOtherSprocket:
What is the math for FPE?  I have a 2250 with a stock 2240 barrel - 177 flavor.  Getting 420 FPS at the muzzle with 7.4 gr.  What does that look like for FPE?

WobblyHand:

--- Quote from: TheOtherSprocket on May 25, 2023, 09:25:10 AM ---What is the math for FPE?  I have a 2250 with a stock 2240 barrel - 177 flavor.  Getting 420 FPS at the muzzle with 7.4 gr.  What does that look like for FPE?

--- End quote ---
You might find this handy:  https://www.pyramydair.com/widgets/  FPE from weight in grains and FPS.

Using 7.4gr and 420 FPS gives 2.9 FPE.

Equation is roughly FPE = m[grains] * v[FPS] * v[FPS]/450124.  Might have the conversion factor slightly off... 

TheOtherSprocket:
Thank you - very helpful

Nukall856:
EdinGa,
  If you add a 14" or 18" barrel in .22, along with opening the end of the exhaust port, opening your TPSleeve using a dremel or you can get a MAP TP. Adding 1 shim to your hammer spring will help a small boost., i get maybe 35+ good shots in 2240x10.1".22. With one #6 splitwasher and the above mentioned modifications. Using a Hammerspring that is stronger < .045> gets a good boost for 20+ shots, but somewhere past 20 shots the fps starts to drop w each shot good for 30 shots,. But,, that is here where im shooting in 60-70F, Lower temp lower pressure, lower shot count so on so forth CO2. Shimming your Bolt o-ring helps with a better sealed breech.
 Doing some or all of the above mentioned, you should get close to 8 FPE.
 My 1322x14" and 2289x14.6" get around 8- 8.5FPE @ 10 pumps, for reference.

NVak

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