Here's my take on it, after having gone back and forth with rifle looney a few times with PM's.
He had the barrel built by another company than T/C. It is not a T/C barrel or a rechamber. He experienced case-head separations occasionaly from the beginning, which to me means a too-long chamber. Then again, the Encore is a break-action rifle, not a bolt, so there has to be a little fudge room for factory brass. He went back and forth with the custom company about this, then eventually gave up.
My take is that the Encore action isn't the best one for fire-forming AI brass. There is just enough spring in ANY break-action single-shot to run into problems.
Plus, there is no reason for the .250 AI in a single-shot--or indeed in a bolt action if you desire anything other than trimming cases less often. It has exactly the same case capacity as the .257 Roberts, which (contrary to some myths) also works fine in a short bolt action.
A rechamber to .257 AI or .25/.284 would work, but the first might result in the same sorts of problems, and both would involve all new brass, relatively expensive dies, etc. All of which makes another barrel in .25-06 seem really attractive.