Inside a gunsafe, I would not use gunsocks - part of the task is meant to be maintaining a consistent, gun-friendly environment inside the safe, but that consistency requires air mobility within the safe. Gunsocks will prevent that airflow.
Magnetic strip would be safe enough, although the repeated rubbing may eventually magnetize the mags, which would mean they'd be prone to pick up ferrous particulates from soil, which could mean otherwise unwarranted failures. So I'd personally pass on that idea.