I think my old thrashed carbine is worth more than a buyback would give, by a long shot. I also simply couldn't believe someone suggested disposing of it to a buyback, even IF it wasn't in perfect condition. Parted out would likely bring far more than a buyback even in less then stellar condition. Geez!
The OP didn't say it had problems or was rusty, he asked if it was likely OK from having sat for so long.
"Far better it is to dare mighty things, to win glorious triumphs even though checkered by failure, than to rank with those poor spirits who neither enjoy nor suffer much because they live in the gray twilight that knows neither victory nor defeat." -Theodore Roosevelt-