It works at 9X and the firing barrel is perfectly straight and polished, just like in all my other weapons made the same way. I have not measured the speed but weighing 0.4 grams, it must be very fast. I cannot hit a soup can at more than 3 meters ... and I cannot calibrate the scope open, because the deviation is random, sometimes up, sometimes down or either side ... The barrel is 280 mm long.. Any idea why? 
I'm going to change the barrel. For some reason, I suspect that the bb`s acquires an energetic rotation movement and that produces the deviation, due to the magnus effect, it is only a suspicion. Thanks for your reply.
I confirm that is the case, a 1800 psi burst disk is typically one you will find on the exit side of a 850 psi regulator on a paintball bottle. A 3000 psi bottle will typically have a 5K disk, and a CO2 bottle will have a 3K disk.
hectmarr wrote:You have to make many weapons, because this field is long and short life
It is a hybrid weapon that burns butane and compressed air. Putting some water in a sound suppressor to enhance the effect is a well-known trick for firearms, the fluid helps to cool the hot gasses and thus lowers the pressure. I would not be surprised if it is a factor here too, heat is certainly important and even HGDT makes a difference between "insulated" and "adiabatic" chambers when calculating power.
hectmarr wrote:You have to make many weapons, because this field is long and short life
