Kroil. Can be Aero Kroil or regular in the can.
If aerosol maybe try not to get on the camo. Maybe a few drips a day for a week or so.
Very gentle heat with a hair dryer. Don't get the camo hot, just a little over warm. Stand barrel on muzzle, the Kroil will creep uphill.
Get some of it back where the choke meets the bore as well. The threads are back there.
Possibly stand barrel up in a few inches of the Kroil in a soup can. May bother camo but a redip isn't all that expensive if it messes up the dip job.
