This is new brass never been sized. Took it right out of the bag and loaded it. I was going up in half grain incraments. Started seeing it at 62 grains had not showen up prior. No there is no groove on the inside of the case. This ring is right where the web on the case head ends. It looks like the case is expanding and the head is not.
If the line is at the jucture of hte case wall and case head, then the line is normal, it is the pressure line. Just took that many loadings working up like you did to get to where the case actually expanded at that point. No biggie. Look at factory brass, there is normally a line at this juncture on fired brass. it is normally by the number of trimmings that a case has seen which detirmines it's life. it is said that if yo have trimmed .004 four or more times it is time to toss the brass. That's conservative, and might hold for full house 22-250 loadings, won't hold for a 30-30 case being neck sized and shooting cast at 1200 fps. A 30-06 being fired at similar levels woudl last what would seem forever. RCBS makes dies that control the growth of brass during resizing, and supposedly increases the life of the brass as a result. Otherwise we are stuck with the old rule, trim to length at first sizing, then trim as needed for every .004 growth, toss when trimmed 4 times like this. Be your own judge, and be careful.
If youtook a hacksaw and cut a case off at this point you would have the head in one hand and the case in the other. The head is solid (except the primer pocket and flash hole of course) and it woud taek a tremendous pressue to expand that enough to see it. If you can measure a difference there, you are getting hot for sure. Takes a blade mic to measure it though.