Fede et al - I got that information about the “D” meaning “Scrap”
from a very knowledgeable collector born in Romania and moving
here as an adult, and reinforced by a Romanian friend of his, still
there, with an interest in ammo.
Regarding the letter “O” on Romanian headstamps, if we are still
talking about 7.9 x 57, I had, when I collected the 7.9 round, 33 Romanian
cartridges in my collection. None that I felt were actually Romanian had an
“O” in the headstamp. I believe, again, if it was 7.9 ammunition referred to
above as also have “O” in the headstamp, there is one steel-case round
so marked: P O-7.92 A 44. While one would believe this is Romanian,
unfortunately, there is a second round of absolutely identical characteristics
except for the headstamp letter font, marked PS O 7.92 43. That would, on
the face of it, be a Czechoslovakian headstamp from the Slovak factory.
Both of these cartridges were found in Viet Nam during the American involvement
there. Again, both, despite headstamps representing two Warsaw Pact countries
(at that time) and with WWII dates, are identical in all characteristics. I personally
do not believe that they were made in two different countries, and I do believe that
the dates of 44 and 43 respectively are spurious. I am not willing to go out on a
limb and identify the factory and country that actually made both. I simply don’t
know. I also don’t know the meaning of “O” since it appears on these cartridges,
one of which supposedly is Romanian and one Slovak. It might even be that in an
attempt to give them a spurious Romanian identity, responsible parties misread the
“D” on actual Romanian rounds to be an “O” and used it in an attempt to somewhat
duplicate the real WWII cartridges from that country. That is pure conjecture on my
part and I it is not a hard-held belief with me, simply one possible reason for the “O.”
I absolutely do not believe, though, that the details of the headstamp are genuine.
I believe they were a clandestine supply to the Viet Cong, who had many weapons
in this caliber, including some WWII MGs, Czech zb 26’s, various Mauser rifles, etc.
And, by the way, to the original question those “Z” clips are of Czech/Slovak manufacture.
I could be wrong, but I think they were the only ones that manufactured that
particular style of stripper clip for the Mauser. They work just fine in a German
K98k, the only rifle I have ever tried them in.