My guess, sounds like a barrel size problem. What size is your barrel? If your paint is close to the size of your barrel, your velocities will be very inconsistent. Seems some of the paint will seal, so will float, so very inconsistent.
If you overbore or underbore you will get treat all the paint the same, so your velocities will be more consistent. My guess is the Spyder was way overbore. As you are shooting a pump, underboring is the only way to go.
Underboring is better anyway, much quieter and more efficient too.