I'm sure there are those on this forum who will know. I have several boxes marked .303 inch Mk 7 I.S.A.A. (under an arrow).
The headstamp is:
R(arrow)L
51
and an upside-down 7.

I pulled a round but the powder is locked in with a tight-fitting wad. So I could not determine if it was berdan. Is this corrosive? Who made it?
Thanx

Regards
XRING
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