I have a 357 pistol pack 2 6 inch, a 4 inch and a 8 inch barrel. I have been shooting with the 8 inch a lot as I have an ultra ot mounted on it. Well I took it off and pu one of the 6 inch barrels on it for about 3 wks. Now the 8 inch will not screw all the way though. It goes right up o the last 2 or 3 turns and then binds up. Both of the six inch barrels will go in with out any problem. I soaked he 8 inh with Cleanoils cleaned it with Butchs but it still will not go though any help please as I really like shooting with this barrel and red dot Thanks Larry