As you have noted, this condition is not normal. The only C96 pistols I have seen with this bowing have had a lot of use with a weak recoil spring, or have been fired with 7.62x25 Soviet ammo (which is too hot for a broomhandle). This condition is serious and potentially dangerous if the bolt does not close fully due to the bowing. You need to have this checked by someone who knows what they are looking at. I have corrected this problem before by TIG welding the bolt window and removing enough of the bowing to ensure the bolt engages the locking block fully. Happy to look at it for you if you bring it to me in New Hampshire. (There would be no charge, since I'm a retired gunsmith)
