The only downsides I see in the 40 are ammo price and maybe lack of availability in the future.

I am sticking with my .40 Sig in my nightstand, but I am accepting that it will get to be more $ to shoot in the future. They've sold a lot of .40 over the past few decades, so I don't think the ammo will be as rare as some think.

Original Post: Consider a Sig 938 in 9mm. I absolutely love mine. Flat, compact....and a damn fine looking weapon. Reliable as well. The thing has to be absolutely crusty with grim before you have any issues.

Yup. even the most "powerful" handgun round fails miserably when compared to even the most "underpowered" rifle round. Shot placement is everything. A well place 9mm trumps a poorly place .44 mag each and every time. Shoot what you can hit with...

Oh, and just as an aside, the myth of "hydrostatic shock" having any bearing on killing or stopping power is just that - a myth. Permanent wound channels do the trick. Pick something that maximizes that.

That is why I prefer the 9mm with less recoil and a quicker recovery to be on target for the next shot.
For home defense, 12 ga trumps all other options.

I guess if the intruder is loaded up on meth' you would need something heavy duty.

But anyone else, a small calibre round is going to stop him doing whatever he is up to. That .38 special bullet fragment that hit me in the chin was like being punched by a large Samoan.

HA! As an old scrummer I can relate!

I have yet to find anyone willing to be shot by my 22 or 32 or 357 😋. As already stated shot placement is critical so whatever you can get repeatable placement use that .

That really is key here - no one wants to be shot with anything.

If there is time to present the gun and convince the perp that that is what is going to happen next, most will demur and find something else to do. The real problems start when there is no time for such niceties, when the party starts sans formal introductions. Then we want something that brings it to a stop as quickly as possible.