From memory, all my files are buried away in storage, this was taken from an original Kynoch drawing. The use of the word “charger” on the drawing is indicative of a British source.
There were about a dozen British makers of these chargers although a paper drawn up for the Cabinet mentions some that I’ve never seen markings from, these might have been sub-contractors as British output of 7,62x54R was huge and there were often shortages of chargers, ammunition cases or bulk packaging.
The only US producer of chargers that I know of was Winchester, theirs have two stamped holes in the base, one towards each end.
Peter.