When to transition?

I have been extremely happy with the Kel-Tec P-3AT as a summer carry firearm. Range sessions have been good, it is a fairly accurate shooter.

Now that fall has arrived, and winter is coming I have concerns about stopping power and or penetration of the .380 cartridge. I plan to research you tube, trusted sites and blogs, and other sources including police personnel, about this issue.

My plan was to transition to my sub-compact .40 cal during fall and winter.
It's frame size is larger, it's cartridge is larger. It can be more easily concealed by my additional clothing, and will better stop a lethal threat - God forbid I ever have to use it.

If I can find evidence that the .380 is capable of functioning thru several layers of heavy clothing and stop a threat, I will continue to carry this firearm. However, if better results are shown with the .40 S/W, I will change to that firearm for the cold months.