Quote:
Originally Posted by dukalmighty
40 S&W is a high pressure load any increase would cause over pressure in guns and cause lots of kabooms
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+1. 9mm, .45 ACP, and .38 Special are relatively old loads, and there are a lot of older firearms and older designs chambered for them, not all of which are up to higher pressures. Hence the +P designation,
generally safe in more modern firearms (follow manufacturer guidance, of course). The .40 S&W is such a new cartridge that manufacturers have confidence in the metallurgy of the firearms and the designs, so they loaded the cartridge to what would have been "+P" pressures from the get-go.