I've shot the Encore platform rifles since I could get my hands on one. Also BH209 when it first came available and I could get my hands on that too. All of my Encores and my current Pro Hunter have seemed to like the 110grs VOLUME charge. (Actually, I use the conversion of (.7) and I weigh all my charges to 75grs by WEIGHT, which amounts to 107grs VOLUME). I also shoot Barnes but, its the 250gr TMZ. I haven't shot the expander in quite some time. I prefer the TMZ and its boattail design, especially for long range.
I shoot a lot. Not quite as much as I used to, at least not this year but, on average shoot a couple thousand or more rounds each year. Yes, I have to replace breech plugs from time to time.
One suggestion and something that I have very good results with, is to seat the bullet on the charge HARD. I have an average bullet seating pressure of between 100 and 105# of force. Two hands and a "T" handle and I thump it pretty hard. Much harder than if I were using pellets of any kind.
My current setup........ T/C Pro Hunter, 209x50, 75grs WEIGHT of BH209, CCI209M primers and Barnes 250gr TMZ bullets w/supplied sabots. This Pro Hunter took a 2x hinge pin right when it came out of the box and before being shot, as even the 1x was to loose. I have a 2# trigger spring, HD locking bolt spring, HD fireing pin spring and both the 44# and 52# hammer springs and also an installed trigger over travel screw. Sear is polished and there is no creap or over travel. I use the 52# hammer spring for target and the 44# spring for hunting, as the 52# spring puts it "on the edge" for hunting by reducing the trigger pull by a couple tenths. Nikon Monarch 2.5-10x50.
I never have fliers, except when I KNOW its my fault (explainable). I did a poll on another sites forum and only 8.5% of shooters responded that they have frequent UNEXPLAINED fliers.
You'll get it dialed in.