Tar/Sar barrels are slightly different from x95 barrels in that they have a pinned on piece of sheet metal for the Tar/Sar's CH to pry on to aid in unlocking the bolt. This piece is to big to fit inside an x95 handguard with out being taken off, I know because I tried.
Also there might be some minor changes to the x95 barrel's gas system where on the Tar/Sar platform the forward sling system would thread through.
You could make the barrels interchangeable with some slight modifications.