Lower pressures/higher velocities
With the same amount of powder Molied bullets will have less preasure and will be slower=You dump in more powder and the velocity goes up along with the preasure. Generaly you can get more velocity with Molly but it takes more powder to do so.
Used Moly years ago. In one 223 I got great velocity/accuracy and it would shot long strings between cleaning(4-500 rounds). Had good results with the 243 shootin mollied 55 grainers too.
#1 It was dirty and time consumeing to coat bullets
#2 The barrel had to be absolutly spotless before you start useing Moly!!!!!!!!
#3 Pretreating the barrel with molly seams to help
#4 You can not go back and forth between coated and uncoated bullets.
#5 If the barrel starts layering molly/copper/carbon the barrel is all but FUBARed.
#6 Moly can collect moisture and rust but I never saw a problem with SS barrels??
After loseing two barrels to buildup I have since just shot bare bullets though others are haveing good results with the new coatings (Boron Nitride, Tungsten Disulfide)
This article might help explain it better?
GUIDE to Bullet Coating