It is possibly the 2nd WW surplus 4831 powder repackaged from bulk war stockpiles. This was used in large calibre heavy machine guns. It was extensively marketed as 4831 by Hodgdons and more recently superceded by H4831 and AR2213. IF its the same stuff, it is a good powder in 7mm rem mags.243win, .308 mag as well.
The above is my surmise only. Others may have better info. ( Note: It is unlikely to be the same as IMR4831, which has different charactetistics.)
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