German 8mm rifle ammo that was used by snipers, primarily in Russia.  The rounds exploded on impact which was nice for the observers but wasn't very good for the one being shot.  There was a lot of controversy over the use of these rounds so their use was supposedly discontinued.  Very rare.

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B.-Patronen made in 1943.  auch fur Tropen means "also for tropics".  

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B.-Patronen made in 1941.