Bob,
What sized belt did you get, and what sized waist are you?
I was on e-bay at lunch and one of the ads specifically said the belt sizes run small (like medium = ladies medium, men's small)
David, I'm not Bob but I can answer your question. The std ILBE main pack comes with a standard issue men's medium belt and will fit 95% of all marines/sailors who wear the pack according to the manual. I'm 34" in the waist and no issues, plenty of adjustment either way.
MtnHtr