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Alan Alford's build

2250b Tube for later move to bulk CO2.
12" .22 Caliber Barrel from Doomsday Backpacker
Brian & Assoc. Alluminum Breech with 2 barrel screws
Original site rear
Pin site on Custom Mt. Airguns Muzzle Break
2x1 Centerpoint Scope with UTG dovetail adapters
Mountain Airguns Custom Bolt and Handle
Mountain Airguns Custom Power Adapter and spring guide
B&A Boss Valve for extra Power

Built mainly for fun and to shoot at local Field Trial Pistol Match.

It currently it shoots a 14.3 Crosman Hunting Pellet at about 530 fps in a 72 degree room for 8.92 FPE.



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18" x 2 x pi / 3 = 37" = ~3', that's an average force of only 14.6lbs.

August 6 2012 at 12:45 PM

dan house  (Login dan_house)
Crosman Forum Member
from IP address 153.90.162.47

(Trying not to hijack James post about his awesome gun.....)

Steve, now that yer back on earth, I ran that same equation thru my calcualtor and got 38.04. Which I supoose is close enough that it probably doesnt matter. But,  as I started breakng it down trying to figure it out, it occured to me maybe I didnt follow the "order of operations" when running thru the equation. But IIRC from my programming class days, Multipication and division carry the same "wieght" and in this case just work it left to right. The other thing I think my have skewed my answer is not using enough places to the right of the decimal point (I used 3.17.... cant mremember more than that...)

I did figure out a couple things on my own: the "/3" referes to the arm moving thru a 120 degree arc, and 120 is one third of 360 degrees of the circle. Still dont understand what the 2 between 18 and pi is, or how you got from 36 inches to 14.6 pounds of effort. the other thing I may not have accounted for is the inches aprt of that... does that have an influence on the arc of travel the pump arm moves thru to the energy needed?

(Edit: Wikipedia says pi is " 3.14159". Which brigns my 38.04 down to 37.69908, and thats much closer to your answer.)



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