Broadsword, those are 7-round mags for a 1958-1960 Mossberg 350K semi-auto, my first rifle. It was used when given to me on my 12th birthday in 1963. I still have it, of course. Any semi auto then was a plinker, not a serious target rifle. The Eley was probably for a bolt action target rifle, like my Savage Anschutz Match 54.
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