Much better-off to just leave it in a air-tight hard shell gun case than an air-exposed gun cabinet. That's why I do (3) things after I fire my last shot at the range.

1) I immediately loosen the breechplug and/or nipple & cleanout/drum bolster screw with tools & ML supplies I keep in a mobile fishing tackle box.

2) I wetten a patch with gun oil & swab the bore... dirty, fouled et..all. That ensures extended protection time should something time-consuming at home occur unexpectedly. Wetting the patch & oil-swabbing takes about 45 seconds of my time.

3) The ML rifle then goes into an air-tight hard shell gun case & never removed or unbuckled until it's time to clean it.

I'll bet you don't do that again! I'll also bet it was Pyrodex... not 777. I've left badly fouled 777 in my bore (in a hard shell case) for 12 days on more than one occasion. No Problemo... as long as the rifle maintains a constant temperature (warm, cool or cold)