Squiffy, if you look at my previous post, I noted that some Vickers I had seen had a khaki or drab finish, BUT their provenance was uncertain at best, etc. I've seen parkerized U.S. rifles from WWI, yet parkerizing wasn't used here until postwar. Of course, they have been refinished postwar. (They went wild with it, parkerizing everything in sight they could find, LOL! Even Indian Wars bayonets for Trapdoor Springfields.)
Warren