We've all had Walter Mitty daydreams about how we'll be prepared and save the day when some big emergency happens. But you won't. When something major happens, chances are very high that not only won't you react, you'll never even see it coming, never even think of looking for it there. If you're even functioning afterwards, the preparation you'll need most will be mental. Some things and tools could be useful - blankets, etc. Guns and shooting are fun, but a hand gun is way down on my list of likely useful items, well below a roll of TP - the multitool I like to wear is far more likely to come in handy.
That is my direct experience of emergencies, one of which left me dead for all practical purposes - the look on the EMT's face in the ambulance told me the odds. That was 24 years ago, before wife, kids and home, so this is all bonus time for me. The other emergencies which involved loved ones and others were the same - never saw it coming.
The above is is true, but if you train regularly and correctly you ca change your odds.
When I was in USMC bootcamp we did a lot of hand to hand combat training.
In high school if I was fighting ,which I hated and still due, if it was a purely physical thing i would typically win due to being 6' tall 215lbs and farm tough muscles. Then one day a scrawny 90lbs worked me over good.
I hated the hand to hand combat training. We practiced slowly on each other for hours a day. Throwing each other to the ground(padded with mulch). I hated it.
Fast forward a few years I was setting in a bar, drinking sprite as I was the DD. A behemoth of a man assaulted me and without any thought I had his hand in a painful control hold. I was surprised as much as he was I think but I was able to make that 325 6'4" man cry like a little girl. I did exactly what I was trained to do. After kneeing him in the face and breaking his nose, my friend and I advanced in the other direction in an expedient manner(cue Charlie Daniels uneasy rider, literally). Found out minutes later that my "buddy" was hitting on this guys girl and he confused me with his friend.
Another year latter I was assaulted/attempted pick pocketed? In town. Next thing I know the degenerates skull was bouncing off the sidewalk and I had my knee in his throat. Again, training was automatic.
In reading I found that even the shape of the targets on the rifle range has a purpose. In early ww2 the navy psychologist realized that most men have a natural aversion to killing another man. The estimated when a man was thrown into combat that only 30 percent of the time would a man place his sights on the enemy and pull the trigger. Most would shoot over the enemies head. This was subconscious. Just by switching from round targets to human silhouette targets they raised this average to well over 50 percent.
Unfortunately the army did not listen,want to know, or cared until officers noticed whole entrenched platoons opening up on VC advancing across open rice patties and getting point blank before being shot, all the while the jungle back drop was trimmed by machine gun and rifle fire 8 to 10 feet up.
Police nationally have a 6% rate of hitting their target. Your average patrolman shoots about two boxes in training every year after leaving the academy. Some such as NYC officers it's more like 25 shots. The success of officers that receive much more training such as swat or gun enthusiast officers that shoot on their own have much higher odds of hitting their target.
So if your preparing, train and not just plain slow fire target training but using correct handling and shooting from cover and reloads. Just popping off as many rounds as you can as fast as you can is useless as well.
If you can't train maybe you should be carrying a 357 snubbie. It's been found that even if you don't hit your target, anyone but the most hopped up junkie or hardened combat veteran and advance into the spectacular and horrific muzzle blast of a 357.