Started reloading for my .22 Hornet last week for the first time. I am using Hogdon's load data for Lil'Gun. The maximum load is 13.0 gr with a 50 cal bullet. The only thing I changed from the load data was COL. I increased my COL to be about .005 short of the lands. After working up to 13.0 gr's I notice what seems to be a slight ring around the case about .020 from the head. I read in my manual that some expansion is normal but I don't know what normal is yet. I took a straightened paperclip and drug it across the inside of the case and didn't notice any groove. Question is do I need to be concerned. By the way, the ring is about .001-.002" Thanks

Actually it is a sign of excess headspace. Most likely the case shoulders are getting pushed back too far when you resize them and then the case stretches when it is fired. The Hornet has that long sloping shoulder on it and cases have a tendancy to stretch easily. Try just neck sizing your cases or just adjusting your sizing die to not push the shoulder back when it sizes the case.

It could also be just a normal expansion 'ring.'

If the ring is very slight, dull looking, and more like a small "bump", it is likely due to normal expansion, as suggested by Gatehouse. If so, nothing to worry about.

If the ring is pretty much smooth, but bright, it is more likely that it is excess headspace for one reason or another, as suggested by Fjold. The brightness is usually indicative of stretching, which only occurs if the brass must move forward to occupy a space.

The Hornet case lends itself to stretching in two ways. First, it is a rimmed cartridge, which would allow it to chamber and fire normally, even if the sizer die had substantially set the case shoulder back. Fired with a set back shoulder, the body stretches to make up the difference. The second factor is that the Hornet case has minimum shoulder and taper, allowing the very thin case to stretch quite easily.

The Hornet case is so thin, I suspect it would have to get pretty bad before the "paper clip test" would reveal a pronounced groove from lost metal. Shining a light into the case mouth may show a shadow prior to that.

I would suggest verifying the sizing die setting to make sure the cartridge case is only sized enough to allow free re-entry into the chamber.