[Jack]

The first thing I'd do is take your pistol down, and use the barrel as your case gauge.
With the barrel out of the gun, try seating your loaded ammo by just finger pressure- slowly. You'll likely be able to tell what the hang up is.
Case gauges do a really nice job of telling you your ammo is within specs, but it can't really tell you if the ammo will seat in your gun- only the barrel can tell you that.
Check also that your chamber is clean- crud build up at the front of the chamber can prevent seating.
I'm going to assume you're using a die that taper crimps- most 9mm dies do. If you are roll crimping, switch to a taper crimp.
Try that, see what happens, and let us know.