You ask if the firing pin springs might just be still very strong from not being used since new. Firing pin springs don't "drive" the firing pin into the primer, the hammer blow does that. It likely has no "rebound" or "retractor" springs, and simple little 3 coil or so sections from a ball point pen, slid over the nose of the firing pin, can often help "retract" the pin after firing. They are simple to install, but do require taking out the firing pins. If your gun has firing pins integral with the hammers, this is not an option. It still may well be that a simple cleaning will solve the problem.
