Not having a .380 anymore I have skipped over this thread until today. I had a Kel-tec, but it was never comfortable to me.
My main carry gun is a Gov. 1911, and my secondary/backup is a S&W 442-2 in .38 special + P (j frame airweight). I use Federal hydra-shocks in both.
One thing I have learned through the years is it is all about shot placement. Whether you are talking about hunting or self defense you want to put the lead in the right place, as needed as much as needed. I have dispatched a 350 lb sow with a cheap .22 lr for a single shot fast drop, several .22 lr that did bring death after a few minutes, a .45 acp that took multiple shots, and .45 acp that I thought just knocked her over but she was dead on her feet.
It has been said on here that the worst carry gun is the gun you don't carry; that a .380 in your pocket is better than a 12 ga at home; etc. I don't care if you carry a 500 x frame, if you don't put the bullet in the right place it will do no good ... alright, with a 500 you could probably get by with just showing it in many cases, but wheter it is a .22 or a .45 the bullet in the right place will do the job.
Also, don't expect the "quick kill" that Hollywood had conditioned us to. You need time to bleed out, and anything hitting vessels will cause this ... eventually. The other thing we count on, and this is where size matters, is the shock of being hit, and hit hard. This would be Mr. Potterfield's "knock down factor." However, people will keep approaching and even get back up after initial shots. Medical examiners, solders and officers will verify that we need to protect "our space," because even after we connect with lead the bad guy can cover a lot of ground before dropping over.
Buy quality ammo, use it in a good gun, practice with your gun, be ready at all times, and pray you never need to use it.