Need help with A5 FPS

Hope somebody can help. Got an upgrade for A5, zero kick hammer came with a spring, installed, took it out for a game.....cant get over 250 FPS out of it now, heard i need harder spring, and others say soft spring, i compared factory spring to the one i got with zero kick hammer and factory spring is larger by about 5/8th of an inch.......so do i need softer or harder spring for FPS to go up?


EDIT: Well after looking into it a bit more and working with the marker i found out that "OD" (outside diameter) of Zero Kick is bigger than original.......causing it to rub against internal part of the marker to the point that it does not cycle all the way back........here is another $100 in the drain.

I hear it will work in some A5's but not all....not all tolerances are the same.

If someone wants Zero Kick hammer that has 200 shots through it PM me, i will give you a HELL of a deal.

pm'd