many of the mags from WWI are two toned, the early ones and had the lanyard loop on the base, then they became blued ( or maybe even reblued??? Even the parkerizing could have been done later, even by an arsenal for their rebuilds but any of those markings would be on the gun itself,,,,,never know...then in WWII they had the makers "mark" on the top ,front edge of the base plate like an R or some other letter...no loops on the WWII mags that I ever saw unless they were put in with or added to an issue gun,,,if only they could talk.....