amlevin
Member
The other day I was at the range shooting some new loads for my AR-15. The rifle is a custom build with a Bushmaster Dissipator 16" barrel.
The range requires single round loading so I was able to inspect each case as it was ejected. One case showed a perfect ring around it, about 5/8" above the base (about the length of a 9mm case from the head). The "ring" was like a scribed line. Closer inspection showed this "line" to be a hairline crack forming a perfect circle around the case.
When I returned home I took a pair of pliers and squeezed the case above the line. As expected the case fractured and revealed a "groove" that extended all the way around the case. It surprised me as it looked just like the groove that appears near the base after a case has been reloaded several times.
The load was a 55 gr Hornady V-Max bullet over 25.3 gr of H4895. The primer showed absolutely no pressure sign and even had a substantial radius on its edge remaining. No cratering of the firing pin or extractor mark. The round fired and sounded just like all the others. The Case was LC 01 marked and this was the first reload. It had the original crimped primer when I processed it. None of the remaining loads showed any similar signs.
Any ideas or suggestions? This seemed to be a strange occurrence to me as most separations have always started just above the web the few times I've had one. Why this far up the case with the same type internal "groove"?
A curious mind wants to know.
The range requires single round loading so I was able to inspect each case as it was ejected. One case showed a perfect ring around it, about 5/8" above the base (about the length of a 9mm case from the head). The "ring" was like a scribed line. Closer inspection showed this "line" to be a hairline crack forming a perfect circle around the case.
When I returned home I took a pair of pliers and squeezed the case above the line. As expected the case fractured and revealed a "groove" that extended all the way around the case. It surprised me as it looked just like the groove that appears near the base after a case has been reloaded several times.
The load was a 55 gr Hornady V-Max bullet over 25.3 gr of H4895. The primer showed absolutely no pressure sign and even had a substantial radius on its edge remaining. No cratering of the firing pin or extractor mark. The round fired and sounded just like all the others. The Case was LC 01 marked and this was the first reload. It had the original crimped primer when I processed it. None of the remaining loads showed any similar signs.
Any ideas or suggestions? This seemed to be a strange occurrence to me as most separations have always started just above the web the few times I've had one. Why this far up the case with the same type internal "groove"?
A curious mind wants to know.