Hi there;How will we know we've shot corrosive ammo? Is it labelled on the box, or is there no way to know before shooting?
The stuff in corrosive ammo is basically a mineral salt (potassium chloride)(or Barium Nitrate) used to preserve the primers for long term reliable ignition. It also has the effect (its salt) of drawing in moisture from the air. This is why people in humid areas need to be more wary with corrosive ammo than people in dry, arid climates.
But yes, it can cause the bore to rust, and if the rust isn't removed, it will pit. Just clean your barrel with good solvent like Hoppe's.
The labels on the ammo boxes lie sometimes (China ammo, Russian ammo and former Eastbloc ammo)
Here is a test to check the ammo labels:
Have a good cigar and regards