Generally, you lose both pressure and velocity when you use moly ... but you lose 'more' pressure than velocity, so you can up the charge weight a bit over what you need with the same naked round, to get your velocity back. It can be extra work to coat the bullets with moly, but most manufactures offer moly versions in the more popular bullet weights.
My experience is that a dirty moly'd barrel is a happy barrel, but I will clean it if it's going to sit a month or more. Doubt if using moly has any real affect on accuracy - there are more issues that impact accuracy greater that the friction in your barrel.
Once I started shooting past 400m, I stopped using 168 SMK ... generally good up to 500m, but there are better bullets out there (Sierra and others). Good luck!
