What is the formula, or best combination of gas pressure, pellet weight, barrel length to get the maximum power? I calculate that the potential energy of the gas that is converted to kinetic energy of the pellet is around 20%. Does anyone have better information than the published gas laws and external ballistics laws? For example, CO2 pressure is dependent on temperature. Taking it to critical temperature, minus 1/10th degree gives about 1,070 psi pressure. Pushing a 0.177 caliber pellet weighing 8.15 grains through an 18 inch barrel puts out approximately 10 ft.-lbs. energy. Of course decreasing the projectile mass will automatically increase the velocity, but decrease the momentum buildup in the barrel travel because the pellet spends less time accelerating. On the contrary, raising the projectile mass will in turn decrease the velocity. So there is a maximum power curve involved, but what is it for the different combinations of psi, pellet mass, and barrel length; to say the least for the caliber, and projectile material, depth of lands and grooves, etc.
Numbers don’t lie, but you can lie with numbers such as manufacturer’s claims and peoples feelings and opinions.
I am not the physics guy to give you an answer, but I do shoot a lot of .177 and .22 air rifles. IMHO, you would need to use a chronograph to get a real answer that doesn’t just reflect spherical cows.
If you have a well-equipped machine shop, you can make ideal barrels, pellets, and firing mechanisms, as well as regulate your gas pressure perfectly. ITRW, manufacturing tolerances vary widely, crucial product specifications are either exaggerated or non-existent, and not every possible combination of factors is even available to try.
I don’t mean this to be threadshitting, I’m just trying to point out that theory won’t necessarily reflect actual performance, if you could even find a product that combines the desired design and necessary tolerances.
You need to weigh your bullets and then use a chronograph to get FPE. That will only Telly you the energy at the point you place the chronograph. If you want to know how hard it is hitting you’ll need to place the chronograph downrange.
Www.pyramydair.com. Sells lots of air rifles. They also test them. They probably tested your gun.
I don’t see how you can claim a 20% efficiency without knowing the valve opening duration. It doesn’t stay open the entire time of the pellet’s travel in the barrel, it is a short burst.
And then there is the burning of some oil during the shot, called dieseling. It becomes more of a factor as the energy of the rifle goes up. Target rifles are lower velocities and generally don’t diesel.
Dennis