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M855 Penetrator (Green tip) is fine to shoot out of an S&W M&P 15, which is chambered for either 5.56mm or .223 Rem. calibers. It has an embedded lead core for more penetration, but other than that, it is a normal 5.56mm round.
I hope this helps.
Yes - that round's pressure is within specs for 5.56x45mm ammunition.
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