Breech plug maintenance: After firing 209 primers, burnt priming compound will coat the flash chamber & the flash hole of the Vent Liner. To clean: remove the breech plug & ream the flash chamber gently with a just under size drill bit (7/32). Use torch tip cleaners to clean the vent liner. Scrub & remove all fouling with the appropriate solvents, & place anti seize on all breech plug/vent liner threads before using the breech plug. Eventually the vent liner will wear out; it should be replaced when it’s interior has opened to .036” or accuracy will suffer. Always use a vent liner in the breech plug, or you may see excessive/unsafe pressures at the primer!!!