Plasma spray arc is the best way to go for hook build-up work--make sure you get the radius of the hook dimensioned first, as maintaining that is critical for proper fit and on face lockup of the gun. I caution against TIG, as too much heat input into the lug- heat travels in metal- and can destroy the braze joint's integrity- and a loose barrel lug is expensive to repair--

"The field is the touchstone of the man"..