Does it really matter what caliber you choose for defensive carry, no not so much. As long as you can do the following.
1. Can you shoot it accurately.
2. Do you have confidence in the platform and caliber.
3. Do you have the mindset to employe the platform effectively.
This debate has been going on for longer the 41 years I have been on this planet. I do truly believe that it won’t be ended with my small post here. The pistol has always been thought of as a secondary weapons system. Meaning that it should back up a primary weapon (most likely that would be a battle rifle .30 cal. or a carbine of mid range 5.56mm/6.8mm/6.5mm). With this said depending on a handgun for you only defensive implement in a gunfight is a flawed thought process from the start. Most CCW calibers are severely underpowered in respects to the long gun, this doesn’t mean that they would not have a positive effect on the threat but you will need more than a single hit to a non central nervous system(CNS) target to render the threat incapacitated.
I have always been a fan of bullets in bunches approach, not saying spray and pray but concentrated effective fire will nullify a threat. This will be achieved by either hydraulic pressure (blood) loss or structure (bone) breakdown. The CNS is at best a small narrow target, at worst it is a small window mounted on a swiveling and bobbing ball (the head). This is why I want as many rounds onboard the weapon platform as possible this will help with two things.
1. I won’t be stingy with bullets (since they are underpowered), I will use enough to do the job.
2. My chosen platform will be in the fight longer as I won’t have to (dare I say this reload as often)
I know some people say that the chances of having to reload in an altercation are small. I just want to be I control of when I have to do so and it not come as a surprise. With this all being said if I had a choice to run or trade lead with somebody, I choose to run. Let me preface this with the following few words. I won’t leave somebody behind to get injured or killed, Take that how you may but I know what I mean.
On to the firepower debate, lets use the full size Glock platform as a baseline. We will use mid-weight bullets this means 9mm(124gr.) .40(165gr) .45(185gr) I have left out the 10mm as somoe people will have a tough time being effective with it.
Glock 17 with 18rnds = 6,555.6 FPE(foot pounds of energy) per magazine
Glock 22 with 16rnds = 7,755.2 FPE(foot pounds of energy) per magazine
Glock 21 with 14rnds = 6,342 FPE(foot pounds of energy) per magazine
All this is only my personal opinion. I have no official training or schooling in ballistics, just a layman’s view is that all modern hollow points will do there job if we are capable of doing ours with the firearms in question.
So as we see the different platforms available energy values do deviate much. I obtained my numbers using a muzzle energy calculator located hear www.georgia-arms.com/mecalc.html
In conclusion it really doesn’t matter if you can control it and do your job the bullet will do it’s job. Please feel free to leave comments if you like.