We don't clean our barrels until they stop shooting good, but cleaning the chamber properly, and often is a must IMO. As stated above 45 cal pistol jag and 1 or 2 patches on it (what ever it takes for a tight fit), and some rubbing alcohol makes quick work of it. Usually just a few wet patches till clean followed by a dry patch.
I had a batch of new 308 brass that did this a few years back. Some weird polish residue left on the brass. You couldn't wipe it off, but within 10-15 rounds after cleaning the pressure signs where back.
Also make sure you are keeping your lugs greased, doesn't take long to fuck up an action with dry lugs and lots of bolt thrust!
I had a batch of new 308 brass that did this a few years back. Some weird polish residue left on the brass. You couldn't wipe it off, but within 10-15 rounds after cleaning the pressure signs where back.
Also make sure you are keeping your lugs greased, doesn't take long to fuck up an action with dry lugs and lots of bolt thrust!