Target Shooting and Defensive ammo
The caliber wars are never ending, but once spin to the argument that in my opinion is not much of an argument anymore, is that bullet designs are becoming more and more effective. When you read about the 9mm vs 45acp debates people argue about the size of the bullet, over penetration and stopping power. The reality is that hunting bullets and defensive ammo has taken a step, maybe not a giant step, but a considerable step forward in increasing a calibers effectiveness.
I was watching a instructional video where the instructor showed bullet penetration differences between a 38 special, shotgun with bird shot, buckshot, a 9mm handgun and an AR15. Most novice shooters would think the rifle was the biggest penetrator and the reality was it was not. It now depends on the bullet design and not the caliber. A fragmenting .223 bullet will transfer energy much easier to soft targets and violently fragment and not over penetrate. Something as mild as a 38 special with a FMJ can pass through an urban home much easier. Your AR15 may be a better option as a defensive weapon if you select the right ammo. If you own a 20inch barrel variant you may want to consider swapping out your AR15 Upper Receiver for something a little shorter just so manuevering inside your home is easier, but it hands down far better than a handgun for most defensive purposes.
If you are new to learning about defending yourself with a firearm, let me answer that question and save you from having to do any research. The answer that you will come to if you choose not to read further and decide to research on your own is NO! Using something as lethal as an Ar15 inside your home makes more sense than using any caliber handgun.
I strongly recommend starting new shooters out on some sort of 22LR bolt action rifle. It doesn’t matter if it is magazines fed or a single shot. Learning the basic shooting skills of aim, hold, sqeeze and learning how to hit the X at 100yds is important. If you are dealing with a young adult, one of the most fun things you can teach them on is a standard A2 AR15 and show them how to use the sighting system and the sighting system.