02-03-2023, 02:05 AM
(This post was last modified: 02-03-2023, 02:09 AM by trianglevelvet.)
A few things:
Headspace - if the headspace is off the head of the case can hit the bolt harder making marks.
Oil in chamber- lubricant left on cases or in chamber increases bolt thrust.
Sharp ejector hole on bolt face-
If the hole has a sharp edge it can bite into the case and make a mark as it rotates when unlocking.
Overgassed system - can try to unlock the bolt before the brass has shrunk back away from chamber walls swiping the case, since the brass is still under pressure when the bolt ia turning to unlock.
Plain 'ol overpressure rounds-
If the round generates too much pressure it marks the case up.
29gr of LVR "shouldn't" be overpressure. But lot variance of the powder, bullet seating depth, neck tension (crimping), and any of the above, or a combination of two or more of the above can cause this.
You'll have to play detective to find out.
Headspace - if the headspace is off the head of the case can hit the bolt harder making marks.
Oil in chamber- lubricant left on cases or in chamber increases bolt thrust.
Sharp ejector hole on bolt face-
If the hole has a sharp edge it can bite into the case and make a mark as it rotates when unlocking.
Overgassed system - can try to unlock the bolt before the brass has shrunk back away from chamber walls swiping the case, since the brass is still under pressure when the bolt ia turning to unlock.
Plain 'ol overpressure rounds-
If the round generates too much pressure it marks the case up.
29gr of LVR "shouldn't" be overpressure. But lot variance of the powder, bullet seating depth, neck tension (crimping), and any of the above, or a combination of two or more of the above can cause this.
You'll have to play detective to find out.