Keeping this in view, can a gun become magnetized?

Short answer: yes. If you have a strong enough magnet rubbing against your gun for an extended period of time (for instance, if your gun was positioned on a gun magnet for a long period of time), your slide and potentially the action of the pistol would become magnetized (note: would have to be a VERY strong magnet).

Also Know, are stainless steel guns magnetic? Yes, most stainless alloys contain enough steel to be magnetic. However, there are stainless alloys that do not attract a magnet. My Mark III stainless (KMKIII-512) pistol is a perfect example. The barrel and receiver will attract a magnet but the lower grip frame does not.

Subsequently, question is, do magnets affect bullets?

Typically, no. Most bullets aren’t ferromagnetic – they aren’t attracted to magnets. The magnet might impart some force on the bullet via Eddy Currents. The same way a magnet falls slowly through a copper pipe, the magnetic field can induce tiny currents in the electrically conductive material, pushing it a little bit.

Are magnets harmful to your body?

High–powered magnet sets are made of tiny and very powerful magnet balls or cubes, often with 100 or more magnets to a set. If swallowed, they can pull together with enough force to cause serious and life-threatening damage to the digestive system.