I've always considered that bulge, which I refer to as the coke bottle look, as a good indication that neck tension is good. It's not a crooked bullet, it's what happens when the case is properly sized down, and then a bullet is forced in, thus producing maximum neck tension.
That bulge can be excessive. This is dependent on the sizing die and the caliber. Sizing dies size to the outside dimension, so one size doesn't fit all brass/bullet combinations.
If your sizing die is tight and/or if the brass is thick, the inner dimension is too small. The coke bottle effect is too much. Maximum neck tension occurs when the brass is maybe about 2 mics smaller on the inside diameter than the bullet, plus or minus a little, depending on diameter, thickness of brass, and brass alloy. Any smaller than that doesn't increase neck tension. It just increases plastic deformation of the brass when the bullet is seated and can damage the bullet. Whenever you see a pronounced coke bottle after seating, that's well more than a couple mics. For jacketed bullets, it doesn't matter, though.
When I expand my 9mm cases with my "M" die (actually a modified Lee die), I get the coke bottle bulge. Before I seat the bullet. I don't know how much more concentric the bullets are, or are not, but this prevents the base of the bullet from being swaged down by the brass - to as little as .353". A regular 9mm expander will way overflare the mouth of the case by the time it expands the brass around the base of the bullet, sufficiently. Many of them can't reach, at all.
The way to modify a Lee 9mm die is to buy the 38S&W (not special) expander plug and put it into the 9mm die body. The cost is $3.00. If you are worried about maximum neck tension with jacketed bullets, you will have to turn it down by a mil. That's how much bigger in diameter the plug is, compared to 9mm. But the important thing is that it reaches down farther into the case.