It is the same size as the WRA co factory 401 cartridge but it’s marked RA 58 with a circle/cross symbol. I’ve got others marked RA 60 all in a box marked .401. From what I’ve learned here and on the web I’m thinking the RA is for Remington Arms and the 58 is the year manufactured and that these are used on military cartridges. Since the 401 wasn’t a military cartridge in 1958, was this case made from something like a .308? Now the .308 is not one of the cartridges recommended to use to make a .401. Usually it’s the 30-30, 35 Remington or 7.62x39. What do the members think?