"What headstamps tell you. Commercial ammunition is marked with the caliber and name of the manufacturer, at least in this country. Military ammunition is stamped with the code of the arsenal or manufacturer and the date of manufacture. Top, L. To R. 45-70 current head stamp; pre WWII commercial Winchester and Remington head stamps – good candidates for being mercuric primed; inside-primed military centerfire from the 1870's and 80's. ""R"" indicates a rifle load, ""F"" is the code of the Frankford Arsenal, ""2 82"" indicates it was loaded in February 1882. Bottom, (left) a Frankford Arsenal round loaded February, 1904. Right, Spencer 52 cal rimfire was made by the Sage Ammunition Works."
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