First, CZ has become my favorite pistol but afraid to use as CC defense weapon. Recently installed Cajun Gun Works Pro Package in my CZ P01. At my age I needed reduced trigger pull and hammer work. Problem.....infrequently fails to fire. Eject bullet and primer has indent. Pull trigger after fail and it fires after second hammer release. This occurs w different ammo and my reloads. Initially installed 8.5 # hammer spring. After reading about some primers not firing and need to use Federal primers only, I changed to the 11.5 # hammer spring. Still having issues. I am considering going to heavier hammer spring but wanted to query others that might have heard, read or encountered this problem? Any suggestions, comments or experience w this problem would be greatly appreciated. Thanksfor helping.