Originally posted by smith crazy:
You are all trying to read much more into this than there is. Let's address the three circled areas in order.
First, the one at the front of the sizing ring. Between the expanded case body and the groove is a soft transition. If this was a heavy load there would be a very sharp line instead of the soft radiius. The circle is around a small nick in the case also, which could have been there before it was loaded the first time and caused from handling.
Second circle, the fine bright line. This is not where a head separation would occur. This is nothing more than what it appears, a bright fine scratch around the case. This could be a result of a small circumferential scratch in the chamber of the gun the case was fired in before its last loading. A scratch/groove in the chamber can result in a slight raised ring on the outside of the case which is polished bright in sizing. More later.
Third circle. This is simply a minor dent in the case caused by an un-burned powder grain that was still in the chamber from the last round which impressed itself into the surface of the case. This is so common as to occur several times in firing a single box of ammunition in any type of gun. We generally don't nit pick every case to death before reloading it and most go un-noticed.
Regarding the defective die scenario. Dies cannot place circumferential marks on a case at any point except where the die mouth stops when sizing, and on the case mouth while crimping. Any other marks from a damaged die will be longitudinal.
There are no marks which would indicate this case was fired in anything other than a revolver. On the 1/3 or so of the rim that is visible there are no extractor or ejector marks as there would be if it had been fired in a Marlin or Winchester lever action rifle. There are also no marks on the case that would indicate there is any problem with the chamber.
All that can definitely be said about this case is that it was fired, re-sized at least once in a carbide die, re-loaded and fired at least once after sizing. Other than that it doesn't appear the case has been polished based on the general tarnish on it.
If there were several of these it is likely that they have been fired several times. The logic behind this is the prior owner was, obviously, a re-loader. Reloaders do not dispose of brass without a good reason, and in this case it was probably because it had reached his self-imposed limit for number of times loaded.
Use it or not, it's your call. Think about it, there is significant gas leakage from a revolver on every shot. Even if you have a head separation, so what, in a revolver it isn't a safety issue. Head separations are extremely rare in straight-walled revolver cartridges of any caliber. The absolutely worst thing that could happen is the head would pull off next time the case was sized leaving the case body in the sizing die. Even this isn't a significant problem as it would be if it happened with a bottle-neck rifle case in a steel die, just a minor inconvenience.
How did this thread get off on such a tangent? All David asked is what caused the groove! Case was over-sized in a carbide die and then loaded and fired again, that is the long and short of it.