The reg came on the bottle already and after the bottle came of its still as tight as ever
Do you mean that the regulator is still stuck threaded to the markers asa?
Double check to make sure the gun can no longer dry fire and that there is no air remaining between the regulator and asa
It either is cross threaded or there is something in the threads sticking.
It may need brute force to unscrew, use something like a strap wrench to get grip and leverage, (baby boa etc)
Before refitting the regulator to the cylinder check all the threads for any damage and that they are clean
Preferably have the regulator and cylinder looked over by someone experienced and refitted properly to the correct torque
Loctite will secure the fit but is not essential provided it is tightened to the correct torque
