I had the Titan 19" many years back ,nice gun. The valving was designed by 'John Bowkett' and was always described as being self regulating.
Dropped mine into a CS 1000 stock and had Dave Welham re-do the breech taper, apparently a known manufacturing issue on the Titan's, and fitted a muzzle break, all done in or around 1992/3 and the gun's still being to this day used by another club member.
I had some great results with it in '94.
Anyway, enjoy it and have fun.