I have a 20 ga. OO grade, made in 1912. It was originally an extractor gun, and fitted with a Curtis forend release. Some time much later, it was returned to the factory and fitted with ejectors. All the numbers match, but forend wood appears to be black walnut, and doesn't match the buttstock.
I am curious about other upgrades that the factory may have offered. In particular, could a gun made prior to 1925 be fitted with a ventilated rib at the factory? If so, is there any way to be certain
if it was a factory re-work?