In the words of Mr Burns: excellent…
cough SCAR-H mags cough 
Bringing this one back.
I was going through my G3 mags and found some non HK marked G3 (aluminum/paratrooper) mags. All my mags are dated from '63-'88.
I have found four Norwegian G3 mags (K with a crown over it) manufactured by Kongsburg. Two were from another German manufacturer, Rheinmetall with their symbol that reminds me of the NATO emblem. And one “G3 P” which I believe are German manufactured mags for Pakistan?
Found this site to be most informative, click on the nation in the column on the left for photo examples of each nations markings.
http://www.mg-42.net/markings.htm
G3P could probably be a German LE magazine. Pakistan is always POF.
Thanks, didn’t know they had a LE specific designation mag.
Also the “G3 P” mags have the NATO stocking number on them which IIRC Pakistan has never been a member state of NATO.
Just speculation on my part, but I’ve seen it on P7 handguns where they had markings that designated them to a specific LE organization.