I'll be interested in others response since I had similiar dismal results with my 25-06 although it is not a TC Encore. I've loaded up fantastic .223 and 30-06 loads but this gun which is my most expensive has let me down.
The only thing I can conclude is we have to keep searching for the perfect load. I have got it down to 1.25" using a Hornady 120 gr bullet and 4350 powder. I even got David Tubbs bore polishing kit which required a time consuming loading of special coated bullets and meticulous cleaning after every five fired rounds. A timney trigger, a bull barrel, a free floating sniper stock, and an expensive Schmidt and Bender scope to top it off...and it shoots no better than my cheapest Rem .223 ADL poor mans rifle.
And to make matters worse all I hear is glowing reports from others how their 25-06's can shoot the neck off of a beer bottle at 300 yards.
I did have a buddy once that had to try 80 plus variations of powder, bullets, primers, and brass to get that magic one inch group out of one particular rifle.
The only advice I have is to keep trying different bullets like
dancoman says. I've tried 90, 100, 117, and 120 gr bullets. I stuck with 4350 and 3031 powder but I think many were saying RL19? and 4895? were the cat's meow.
Believe me I almost wanted to send mine back too.