Any time you put a new barrel in a stock, you are going to have to consider how well that barrel "FITS" in the barrel mortise of the stock. With a T/C, there is also the fit of the hook to the breech/tang. A lot of times, that barrel Moves in recoil with the first shot and then settles in for the next shots. It can drive a shooter NUTS.
Are you still switching barrels with the original, or is this newer barrel a true Replacement? If its the latter, then consider rebedding the tang and barrel mortises, at least out to the Wedge. That will eliminate movement of the barrel in the stock when its fired, and should keep the same POI for the first and subsequent shots.
If you are still wanting to use Both Barrels in the same stock, you may not be able to bed the one and get the second to still fit. A lot of careful measuring has to be made. Sometimes, just bedding the bottom flat of the barrel channel is all that is needed, and then both barrels can be installed and used.
I would start MY investigation by putting marking dye on that hook on the new barrel, putting it into the tang to see what is rubbing, and WHAT ISN'T!!! Then put the old barrel with marking dye on that hook, so you can compare the two. I suspect that you will find that one hook is rubbing in a place where the other isn't, and that may be the sole source of the problem. :idunno: :hmm: :surrender: :thumbsup: