Riddle me this...
I was full length sizing some 6.5 Grendel cases when one of them felt different going thru, more resistance. When I pulled it out it had formed a ring on the outside near the case head. It was as if the sizing die wiped brass down the case body as I moved it up into the sizing die. This happened for a total of 5 cases, the rest ran thru fine.
There are some clues to this mystery:
These cases I used to test some different powders, on 5 cases from that test I hit pressure and stopped shooting. 3 of the cases that are now ruined I know are from those 5 because I could see the extractor mark sign of pressure, 2 of the ruined cases Im not certain but the total number adds up to the notes from that day. I suspect, these are all the 5 cases I noted high pressure. Side note: before sizing I hit the pressured case heads gently on a stone to remove the extractor mark and a ejector mark burr but I still know which ones they are.
All these cases are on their 3rd firing, so before sizing I measured their case headspace to compare to 1x and 2x just for my notes. All the cases I measured were either 1.220" or 1.221 with one case 1.219". I measured only 12 sample of 17 cases. I didnt keep track of the ones with the pressure marks but assume some were in there and measured the same, so there wasnt a measurable difference between these when unsized. There wasnt any visual difference either, again the ring formed in the sizing process.
My best guess is the overpressure ruined the cases but how? Has anyone experienced anything like this or know what happened?
Now for the pics. In one pic there is a normally sized case on the right for comparison.
I was full length sizing some 6.5 Grendel cases when one of them felt different going thru, more resistance. When I pulled it out it had formed a ring on the outside near the case head. It was as if the sizing die wiped brass down the case body as I moved it up into the sizing die. This happened for a total of 5 cases, the rest ran thru fine.
There are some clues to this mystery:
These cases I used to test some different powders, on 5 cases from that test I hit pressure and stopped shooting. 3 of the cases that are now ruined I know are from those 5 because I could see the extractor mark sign of pressure, 2 of the ruined cases Im not certain but the total number adds up to the notes from that day. I suspect, these are all the 5 cases I noted high pressure. Side note: before sizing I hit the pressured case heads gently on a stone to remove the extractor mark and a ejector mark burr but I still know which ones they are.
All these cases are on their 3rd firing, so before sizing I measured their case headspace to compare to 1x and 2x just for my notes. All the cases I measured were either 1.220" or 1.221 with one case 1.219". I measured only 12 sample of 17 cases. I didnt keep track of the ones with the pressure marks but assume some were in there and measured the same, so there wasnt a measurable difference between these when unsized. There wasnt any visual difference either, again the ring formed in the sizing process.
My best guess is the overpressure ruined the cases but how? Has anyone experienced anything like this or know what happened?
Now for the pics. In one pic there is a normally sized case on the right for comparison.
. I used to use one shot quite a lot and was a big proponent. However, between the breathing of the aerosol and inconsistent case forming results, I switched to the homemade lanolin/ 99% isopropyl concoction. Forming force and case dimension consistency have improved vastly, not to mention no more ingesting the aerosol. It is also much cheaper. Try it you might like it.
