I just purchased one in 45/70. Sorry to say I haven't fired it yet. Here are a some preliminary observations. By the way, I am new to the Thompson Encore.
I have read several threads that says the throat is non-existent in the 45/70 and looking down the barrel that is what it looks like. However, I have some Remington 405 grain bullets loaded for my lever action and they chamber just right. C.O.L is 2.550
I have a standard encore (not pro-hunter) with black synthetic stock and for-end. My fore-end is just a touch narrow. Screw holes are correct. I put some sandpaper on the correct size tool socket and a few minutes later it fits fine. The 26" barrel still fits and looks good. I'm still curious as if the 28" PH is the same diameter as the 26Ē or if it is larger like the 20" Katahdin.
I really would like to mount some sort of small red dot on it and keep the peep sight. However, the peep is using the holes for the scope mount. It is a one or the other affair. Front sight has a screw in it. I havenít tried to remove the front sight, but it looks like it will come off.
I like the looks feel of the 20Ē 45/70 Katahdin and donít plan on getting rid of it anytime soon. I also hope to shoot it in the near future.
I hope this information helps about the Katahdin.