I am reloading 9mm rounds on a Dillon XL650 press with 115Gr. FMJ bullets from Montana Gold. I have measured the bullets and they are .355 inches at the base. After resizing in stage 1 of the press and loading and seating the bullet, if you look at the finished round the case is smaller in diameter near the center and the bullet makes a clear mark from the top of the case to the bottom of the bullet inside the case. Now it is not much, but you can see it. The measurements are:

Top of case .376
Center of case .374
Head .386

I get the same look with once fired and new brass. I have shot over 200 rounds with no issues, so should I worry?

Thanks, Gary

The 9mm is a tapered case. a Carbide sizer makes it straight sided. It is very normal to be able to see the bottom of the bullet. Shoot and have fun.