And you have NO idea......
You have NO idea how much overpressure a round has and there is no limiting cap on the pressure.
FWIW, from page 11 of the M&P owners manual:
• "Plus-P-Plus" (+P+) ammunition must not be used in Smith & Wesson firearms. This marking on the ammunition designates that it exceeds established industry standards, but the designation does not represent defined pressure limits and therefore such ammunition may vary significantly as to the pressures generated and could be DANGEROUS.
You have NO idea how much overpressure a round has and there is no limiting cap on the pressure.