My stock a-5 barrel has started to screw up. it has got to were it will fire and about 15 yds downrange and suddenly swoop to the ground. It doesn't just fall to the ground it rapidly moves toward to the ground. What is happening? Any idea how i can fix it. it is causing my apex to lose effectiveness because it has to compensate for the downward movement of the ball. could it be a high velocity, low velocity, other issue? could my paint be small and air exiting over paintball cause topspin?