I recently purchased a quantity of surplus .30-06 brass and while sorting-out the ones with Berdan primers, came-across some Boxer cartridge head-stamp markings that I was not familiar with.
Perhaps someone here can answer my identification questions? What are they???
I have the following -- all in .30-06 brass:
1) - FA-30 NM - the neck diameter appears to be smaller than the .30-06's standard .308 dimension.
2) - RA 1941 - 300-Z - I've never seen the "300-Z" designation before and don't know which arsenal is "RA".
3) - U.S.C.Co. - 18
4) - SUPER-X 30-G-1906
Also, numbers 2 and 3 above have a deep groove machined, pressed or cast into the brass base of the cartridge, apart-from but completely surrounding the primer pocket and I have no idea what its purpose is.
About the ring surrounding the primer pocket - it does not appear to be a crimp ring because it is located way outside the primer pocket. On number 3, above, the space between the primer pocket and the ring-groove has three indentations pressed into it each exactly 120-degrees apart. I have dealt-with primer crimps before and have swagged them out; but all of them have been inside the primer pocket cavity, just inside the pocket's wall. This strange groove is separated from the primer pocket by at least 1/16th of an inch and completely surrounds the pocket. This groove looks like an outer ring on a target, where the primer pocket represents the black center of the target. Any help would be appreciated? Thanks!