Ah cain't help bein big.
Yes, I had a problem 209x45, one of the early ones with 1:20 twist and (worse) a washboard barrel. TC replaced the barrel with a newer 1:28 twist and better rifling job. That one might have shot okay with QLA in place but I didn't give it the chance. By that time I was convinced the QLA is a needless and problematic part of a TC barrel for conical use. The local gunsmith was a friend of mine (now gone from this world) - he cut the barrel off just at the beginning of the QLA andput ona nice 11ยบ target crown. He also cut and rethreaded the ramrod to match the length. If I told you what he charged me you would faint.
Let's just say it was not expensive. The crown was well done but that type crown is not the best for loading flat based, bore-ridingconicals. Tapered conicals might be fine with such a crown but that isn't what I shoot. I redid the crown myself using a cordless drill, a grinding cone and ball, some patches, grinding compound, and finally polished it with JB Bore Paste on some patches.
Please ignore the lint and color artifacts. I think it came out nice and the rifle now loads much easier. That Encore had other problems as well, but I finally whipped them all. It will now shoot conicals just fine and shoots the sabots equally well. The only drawback I now find with the rifle is recoil from the conicals. Unless you happen to be the Joe Average the strange looking Encore stock was designed for (and I'm not), heavy conicals over any substantial charge will kick like a mule. There are certainly better designs for conical use.
She mostly just sits in the cabinet nowadays - no hills left to climb.
If I were to pay to have that same work done, I would go with David White at
http://www.precisionrifleworks.net/ I believe he outlines his pricing in the forum. I've found TC did a better job generally with the blued barrels than the stainless, a situation that has surely been rectified. If you insert a tight fitting patch in your rifle's (very clean) bore then slowly push it down, do you feel variations in the pressure required? If so, removing the QLA is likely going to be of little benefit. In that event, I would contact TC and strongly request a replacement barrel.