Several 9 mm pistol owners I know claim it is best to use the 9mm 124 gr +P rounds during the warm months and the 147 gr standard pressure rounds during the winter months, when a bad guy may be wearing a heavy winter coat. Any thoughts from 9 mm owners as to whether this thinking has any merit?
According to Speer's ballistic tables, their 124 gr +P rounds puts out 417 ft lbs of energy at 1220 ft per second from the muzzle of a 4" barrel.
The Speer 147 gr standard pressure round puts out 317 ft lbs of energy, traveling at 985 ft per second from the same 4" barrel.
It would seem to me the 9mm 124 gr +P round beats the 147 gr standard pressure round regardless of season.