From Egyptian Secrets of Albertus Magnus, Joseph H. Peterson edition:
To prevent Fire Arms from being Bewitched.
Take nine blades of straw from under a sow while she is nursing young pigs, therefrom put nine knots into the shaft and insert them between the two barrel loops, and such a gun cannot be bewitched.
The grimoire Egyptian Secrets of Albertus Magnus lists this spell.
Timeline of related events
1725Publication of Egyptian Secrets of Albertus Magnus (lists this spell)
1869English-language translation of Egyptian Secrets (lists this spell)