Not bragging, but a bit of my creds may help a bit here. I’m a 30 year retired LEO who was the Rangemaster for his LEA for several years. I've competed in IPSC and IDPA. I was on a SWAT team for three years. I worked in a team that investigated OIS and I've seen a couple of dozen autopsies that resulted from shootings. I've spoken to pathologists for hundreds of hours about causes of death, by all kinds of weapons. I'm the senior instructor for a very busy firearms training school and I've been instructing for about 30 years.
The .38 is the personal minimum caliber for my needs. Quite a few people will carry less powerful calibers, and they often discover too late, that they're under gunned. There may be reasons why someone may lean this way, but absent them, I prefer a more powerful round. The opposite opinion says, "It's better than a pointy stick." And it is. But not by much.
So can a ".38 revolver." The difference is that it's rare that the auto can't be cleared in a few seconds. OTOH, when a revolver jams it usually needs a well‒lit workbench and some tools to repair it. There's a reason that military armies the world over, have switched overwhelmingly to semi‒autos.
When carrying a semi‒auto, a round should be chambered BEFORE putting the gun into its holster. That way one NEVER has to cycle the slide to chamber a round when a threat appears.
As I've said before in this thread, GET SOME PROFESSIONAL TRAINING! If you're still scared about this happening, carry one of the numerous striker‒fired firearms available these days, like the Glock. They do not have a manual safety lever.
Only someone who is committing a crime should find this information of value. If you're in a shooting, unless you're still being threatened after the assaulter is down, e.g. an angry crowd, his crime partners, etc., you'd better be on the scene when LE arrives. If you leave, you WILL BE REGARDED as the suspect and will be treated accordingly when you're located.
While both are possible, I've seen many jacketed rounds that could not be matched "to the weapon's barrel …" and many wadcutters that could be matched.
It happens, but USUALLY it's because the person didn't follow the law. or did something extremely stupid that he heard through folklore, such as moving the body to put himself in a better light, or adding 'evidence.'
Which is why I suggested PROFESSIONAL TRAINING. A good CCW class, or even a basic firearms class should present info as to the law covering deadly force, and when it's appropriate, when it's not, and how you will be judged after a use of it. Trying to get that info from your next door neighbor, your BIL who is a police officer, or your uncle who was "in the war" is a bad idea. Far better to stick to a criminal defense attorney who is well versed in self‒defense law. Here's a hint. MOST criminal defense attorneys are not.