9MM 124 +P vs 147 gr standard pressure
It would seem to me the 9mm 124 gr +P round beats the 147 gr standard pressure round regardless of season.
Consider what your goal is. You are choosing a projectile which is to cause incapacitation of a determined deadly threat as quickly as possible. Over 90% of the time the mechanism of incapacitation will be blood loss due to crushed vascular tissue (due to a human body's structure).
When the 9mm bullet impacts the threat it has a diameter of .355". You want that bullet to deform to a greater diameter as quickly as possible after impact, but not so much that it will have insufficient penetration to cause massive damage to induce massive hemorrhaging.
How much penetration is the subject of debate.
There is a chance with some hollow point bullet designs that clothing will plug the nose cavity and thereby prevent deformation. That will leave you with at maximum a .355 crush column. This is not
optimum. More clothes, more chance the nose gets plugged.
Considering that the two cartridge loadings to which you refer have open hollow point bullet designs; I would reason that they are equally likely (or not) to suffer a plugged cavity due to clothing.
So choose the load which your gun digests best and you shoot best.
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