From Egyptian Secrets of Albertus Magnus, Joseph H. Peterson edition:
To cause Rifles or Muskets to miss Fire.
Speak these words: AFA AFCA NOSTRA, when you are able to look into the barrel of some person's gun and it will fail to discharge; but if you desire it to give fire recall these words backward.
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)