Seeing where the bullets ends is normal. The bullet expands the case wall creating neck tension. Shaving lead however normally means you aren't flaring the case mouth sufficiently. You need more than the bevel base of the bullet on lead bullets. The case mouth needs to be larger than the bullet OD after you flare them. So from your measurements, you aren't flaring them enough.

I would suggest you remove the old lube. It shouldn't make a dimension difference, but it can create other problems.

I included a picture of some 357 Mags I loaded so you can see the bullet base as it expands the brass case.