The real diffrence in the m25 and the m62 is;

m25 tracer 30.06- (or early versions t10) has a 145 gr bullet with 50 gr of IMR 4895 powder and travels 2665 fps. The tracer compound contains compostion R 321 which is 16% polyvinyle chloride, 26% magnesium powder, 52% strontium nitrate.

m62 tracer 7.62x51- has a 142 gr bullet with 46 gr WC 846 powder and travels 2750 fps. The tracer compound contains compostion R 284 which is 17% polyvinyle chloride, 28% magnesium powder, and 55% strontium nitrate. (Also used on m196 .223)

and just to throw in;

m276 dim tracer compound is compostion R 440 which is barium perioxide, strontium perioxide, calcium resonate, and magnesium carbonate.
wolf