Thread: Tight chamber and marks on projectile

Originally Posted by johnd

To me it looks like...
On the left side of the 'line' is the transition into the barrel (a bit further down would show the lands) on the right of the line is the chamber.
The line is the build up of carbon ahead of where the case finishes. It may be deep enough that now the projectiles get scratched, depending on their shape.

Left side is chamber and right side is barrel.

Definitely a carbon ring there. CLR on a nylon brush spun in the drill on the end of a cleaning rod will sort it asap. Just remember to thoroughly clean the CLR out with meths or alcohol. Then oil straight after, then a final dry patch.
Dry the chamber and barrel of CLR before rechecking with the borescope to check progress and then clean out CLR with meths etc.