What powder were you using? 777 is noncorosive and you can leave your gun for a week or two without too much adverse affect I have been told.
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All 777 powder-varieties are somewhat corrosive.... dependant upon outdoor weather/barrel conditions prior to cease of use. I have tested an uncleaned 777 rifle for 12 days & it worked terrific, but I kept the rifle in an hard-shelled case with indoor temperature surroundings. Every test has different variations. Try to clean immediately after use. Odds are -- if the rifle was subjected to open-air conditions, some type of bore damage has occurred.