O.K. I don't mean to beat a dead horse but here goes, I have done some investigating about pressures and 223/243 wssm and have come up with some interesting things, TC offers factory barrels in both the 300 winmag, a 375h&H and of course the 22-250, In regards to the "Back Thrust" issue the 223/243wssm has a head dia of .535" the 300 and the 375 have head head dia of .532 for a grand differance of .003" not much when you look a .003 on your dial indicator.
Well thats answeres that, and for those that would say .003" is alot, it is about .005% larger.
Now onto the next issue of pressures the 223/243wssm has a max pressure of 65,000psi, the 375H&H has a max pressure of 62,000, the 300 has a max pressure of 64,000, using the 300 winmag as a control, that is less than a .02% differance in ABSOLUTE MAXIMUM pressures, so the line about overboard pressures is a hard pill to swallow, In comparison the 22-250 max pressure is also 65,000 psi.
Bottom line is according to what I have read here on this post the encore shouldn't be chambered in a 375H&H or 300 winmag for the same saftey reasons it is not chambered in 223/243.
In todays age of lawers I find it hard to belive that the encore would only have a .02% pressure saftey margin biult into it.
I guess I will have to call the TC and get there input, I might be missing something.