As mentioned that wouldn’t have happened from routine cleaning from the chamber end. Even if one cleaned it daily. Thousands of explosions in chambers, with the head expanding and contracting against the chamber wall doesn’t cause it. Normal cleaning from the breech certainly isn’t going to.
However, have seen some of the more recent shells that don’t use brass heads stick in pumps. Have had it happen with some of the economy grade Winchester’s. Use brass head shells and it no longer happens.
