I was shocked also. I was reading their manual online looking for some information about a trigger on a M&P and found on page 12 of theirbadkarma56 wrote:Still, I am surprised that a major manufacturer like S&W would make such a blanket statement. Perhaps this partly explains why none of their weapons seem to be standard issue these days...
manual. . .
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“Plus-P� (+P) ammunition generates pressures in excess of the
pressures associated with standard ammunition. Such pressures
may affect the wear characteristics or exceed the margin of safety
built into some revolvers and could therefore be DANGEROUS.
This ammunition should not be used in Smith & Wesson
medium (K frame) revolvers manufactured prior to 1958. Such
pre-1958 medium (K-frame) revolvers can be identified by the
absence of a model number stamped inside the yoke cut of the
frame. (i.e., the area of the frame exposed when the cylinder is
in the open position.
“Plus-P-Plus (+P+) ammunition must not be used in Smith &
Wesson firearms.