On another range trip with the 15lb. recoil spring I did get another FTF. Only 1 out of 50 this time, but that is still too many. Installed a 16 lb. spring and did not get any FTFs. Thought I experienced a delayed feed as described previously, but I may be overly critical at this point. So, I got a 17 lb. recoil spring for a Hi Power and so far it has run without a problem for the past two range trips. It is defintely stiffer and harder to rack, but it does feed everything now. I am going to stick with the 16 and 17lb. springs, as they are reliable. I am also trying to pay more attention to controlling trigger reset. So, seems like problem solved by recoil spring.