Not sure if this should be in the reloading section or not, let me know if you guys think so.

So I got some 9mm cases at the gun show over the weekend and I got to cleaning them and noticed a slight taper of the cases just above the extraction groove toward the mouth. Very subtle but measurable, I would not call it a bulge however. New to this so I have a questions. Is slight expansion expected after firing 9mm? Will resizing get the case back to tolerances deemed safe or abel to chamber?

Does anyone have a diagram that shows the measurements that a 9mm case should be at?

If you guys need I can post measurements to make things clearer. So far I have randomly picked 12 cases from 50 and all are nearly the same in measurement but just have that subtle taper just above the extraction groove towards the mouth

Thanks guys.

Does this help

Different guns will have different expansions on the case. HK is nasty sometimes so is the Walther PPQ on the cases.

Im sure it would get more attention in the reloading section. Not sure about this expansion that your talking bout a picture would be helpful. I've heard that some guys get excessive bulge from glocks. Were these cases sized already? If not run them through your sizing die again take out your barrel and see if the cases will chamber. You should also  get a case gauge.. Heres the saami specs for 9mm

if you look at the diagram posted, the 9mm is tapered. Are you referring to a bulge? Bulging is normal and usually does not cause trouble.
Lubing the cases before resizing will help.

Or the coke bottle affect after reloading.... I think majority of 9mm reloads look like a coke bottle.... Some dies are different but the coke bottle round works as long as do a chamber check or use a case gauge....

Look like this?

Or the coke bottle affect after reloading.... I think majority of 9mm reloads look like a coke bottle.... Some dies are different but the coke bottle round works as long as do a chamber check or use a case gauge....

Look like this?

Exactly like that. I have not resized yet but will and then check again.

Does this help

Perfect, it helps. Thanks

^^^The data is good for the bullet and powder it's used to reload with.  Generally heavier bullets are longer and the ogive(?) will affect the COAL (and bullet seating depth).

In short, buy a manual for the bullets you are using.