oooh, thats good stuff. I use it before some JB bore compound on really nasty barrels, it works great--it cuts through and loosens up stuff real nice. I highly recommend it. :grin:
Its a penetrating oil; use it straight from the can. It has slight lubricating qualities, but its primary use is cleaning.
I run a patch wet with Kroil thru a warm bore before I leave the range, while the barrel is still warm. I usually clean the following day, but longer is OK - the Kroil continues to "work" while it sits.