If you've lubed the poppet o ring, and its made no difference have you tried changing the battery for a new one, a decent brand one like procell etc? Also what are you using to chrono it, and where?
I was using the sites chrono not sure of make or model etc on their practice range.
Battery wise i was using an energiser one. Have just got some replacement annsman lithium ones from my inlaws, so will try them out when i go back and see if it makes any difference.