Where the chamber enters the receiver is almost not affected at all I don't know what you are seeing there. the worst looking part of the barrel is just past the gas ports and as bad as it looks and that is the deepest pit the depth of the pit is actually no deeper than the thickness of a business card. Before I cleaned it up I thought that area might go through. but it ended up being alot shallower than I thought it was. This is definitely the worst looking gun I have ever had the pleasure of making usable again. Before this the worst one I cleaned up was my 870 I bought that had been buried underground.The rust pitting/cancer is probably the worst I have ever seen. Looks like it almost ate it's way through the barrel where the chamber enters the receiver. Looks dangerous to me. Might not be though, I'm no metallurgy expert.