Never had what you are describing happen and ive had many Lehigh conversions. Worst i had was having to fire again on a spent Fed209A primer. Never an issue with a Win209. Just for giggles, check the size of the flash hole in the vent liner. Maybe you got a bad one. If its over .036 its bad. They are around .032 or less new. If you are getting between .003-.005 crush on primer this should not be happening.