Asked the question myself a couple of weeks ago when I was offered some take-off BT-99 barrels.
Got answers ranging from "They will all interchange"...
To answers from reputable gunsmiths saying "None of them will interchange without gunsmithing work which would exceed the difference between the price of selling the one you have and buying a new BT-99 with screw-in Invector Plus chokes."
I purchased a 34" barrel to go with my 32" BT-99 that I had.......No, they will not interchange. The amount of smithing required will range from very little to a whole lot......maybe even changing the barrel lug. Good Luck!
My barrel work was done by Doug Braker in Minnesota & he did a great job.