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Gary Hindman's Custom Model 113 and Model 114

Both guns are bulk fill. They have a silver finish on the barrel and the CO2 tube. Stocks have been redone to a natural finish. Simmons .22 3x9x32 AO silver scope and rings are connected using IA mounts

Model 113- Predator Polymags .177- 5-shot groups @ 25 yds. =.440" C-C - Avg. velocity 697 fps 25 shots ( high 721 fps)

Model 114 - JSB Exacts .22 - 5-shot groups @ 25yds. = .54O" C-C- Avg.velocity 654 fps. 25 shots (high 660 fps)



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Well, a couple of things.

July 5 2012 at 2:44 PM

Steve in NC  (Login pneuguy)
Troll, Banned User or Assorted Delinquent
from IP address 74.242.231.138


Response to Question about the "Valve Ineffectiveness Chart"....

1. The basic idea behind "Sonic Horizon" was, due to the fundamental limit imposed by the speed of sound on the speed of propagation of pressure change, it makes no difference to the acceleration of the pellet whether the valve closes or remains open after the pellet crosses the "Horizon," because the pressure change created by the valve closing (or not) can't reach the pellet before it departs from the muzzle. In other words, the only gas that can contribute to accelerating the pellet in the example MV = 850fps case, is the gas occupying the first 33% of the bore. That is to say, 33% of the volume of the bore.

2. When air expands in an airgun, the expansion is so rapid that no significant heat has time to transfer from the walls of the bore etc. to the air. That is to say, the expansion is (to a good approximation) adiabatic. Under that condition, pressure isn't inversely proportional to volume, but (because air is effectively a diatomic gas) to volume raised to the 1.4 power. Therefore, for example, doubling volume wouldn't reduce pressure by factor of 2, but by 21.4 = 2.64.

Steve

 
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