Have a look under the manufacturers section, there is loads on there regarding this, if it makes you feel better you are not alone with this problem, solutions range from cleaning the barrel to having it recrowned.
HW 77 V glide kit by Steve Pope
8-40x56 Custom Shop.
HW 101. Big Nikko. Ginb FT Stock.
Webley Omega, Gas Ram.
Rohm Twinmaster Trainer.
Red Dot Sight.