I just picked this Frankford Arsenal tool up for a song. I have 2 others that are Military inspected and dated 1901, 1895.
This is a late one that is larger, longer, and normally unmarked for the 30-06 rifle round.
After cleaning it up some I found a cast marking on the left side frame. See photos
It looks like;
STD M 1
Standard M1 Rifle?
I’m amazed by this cast marking. I thought these tools were discontinued by 1907.
Hard to get a clear photo but with my loop I can clearly make out those letters and number.
The M1 would take these tools up into the 1930’s.
Murph