(Actually I'm surprised there isn't a sticky on this, or a number of threads that I could have found)
In looking for a new home defense handgun I'm obviously faced with a ton of choices in cartridge. I was reluctant to discount any because there had to be good reasons why the various law enforcement and military agencies select certain ones, or why civilians buy a certain type. However it occurred to me that the requirements for military and law enforcement weapons might not be so relevant within the confines of drywall and ranges likely to be within seven yards.
So as far as I can tell, these are the reasons for the popularity of various popular cartridges and my thoughts on them. I'm hoping you guys can straighten me out if I'm off. Also what cartridge do you use for home defense and why?
.25, .380, .38 special etc - The best gun for defense is the one you have, so I appreciate these for their ease of use in concealed carry, but is there any reason to select these sorts of rounds when you could have a full sized gun?
9mm, 5.7 mm -allows for a smaller gun for more comfortable carry without sacrificing high capacity. Also they are supposed have better armor piercing capability, but that's with military rounds as opposed to home defense hollow point variants. Also popular militarily for the lower weight of the rounds compared to a .45. Important when on the march or when you're having to deliver supplies around the world and into the middle of some desert or Jungle backwater, not so much a consideration for home defense.
.40 S&W, .357 Sig -These seem to be getting quite popular, particularly the .40. But the draw for their creation and use by law enforcement seems to come from their external ballistics at range compared to the .45. That is very important if you're going to be in a shootout while taking cover behind your squad car parked down the street from your assailant. But it doesn't seem nearly so relevant to home defense. Maybe if you've got a McMansion. But again I'm not expecting to get a shot beyond seven yards, and never more than 14, which would require me to be twisting around a staircase and them to be in the far corner of a room I could just barely see into from there.
.357 magnum, 10mm- My understanding is that the reason the .357 magnum exists is because law enforcement wanted a handgun that could punch through a car door and still take a guy out. With the slope of my yard I think I'm safe from having a home intruder crash through a wall. So all you may get for the extra recoil and the smaller hole, just turns into burying the round deeper into my wall or my neighbors. I also understand that these rounds have some popularity for being able to take down game or threats at 100 yards. But I wouldn't want to try and explain a 100 yard "defensive" shot to the police.
.45 ACP - nice big deep holes without a lot of flash or much more recoil than 9mm. It seems like the round to choose for home defense, if you've got big enough hands. 45 GAP sounds like it hasn't been so popular for some reason, with only Glock still trying to push it.
.410 bore - With a case that long I'd have though it would have a lot of potential. But everything I've been able to find indicates that you do better with a traditional bullet over the slugs, and the penetration just isn't there with the buckshot or disks, and the spread hurts shot placement. It'll still spoil someone's day, and you are making a number of holes instead of just on, but not what you want to have against a big guy in a heavy coat. I don't know how much difference it makes, but all the penetration tests I know of occurred with some distance to the target, like 25 feet or more. I wonder if things are quite different at 25 inches. Besides not losing speed to the air, you'd think they wouldn't have spread much and the first would weaken tissue and break bones ahead of the rest.
.50 AE - While I could appreciate the raw intimidation of a Desert Eagle, it sounds like this isn't popular due to the flash and recoil one gets compared to the increase in wounding. Also at something like a buck fifty per shot I have concerns about how much I'd practically train. Still though, if my efforts at work and the gym result in a promotion and a grip of iron, might this be a better option than a .45? Or for a given arm strength are you going to still be able to fire more accurately and faster with a .45 and therefore come out ahead?
Big revolver rounds- same problems as the .50AE except in a less convenient form.
Of course those are the things you could put in a handgun. I've been giving thought to the idea that none of the handgun rounds really match up with a full power rifle or shotgun. But handguns are just easier to keep closer at hand, and I think that might be even more important.
Though I'm considering going with a handgun for getting rushed, and a shotgun for "honey, did you hear something?" situations.
In looking for a new home defense handgun I'm obviously faced with a ton of choices in cartridge. I was reluctant to discount any because there had to be good reasons why the various law enforcement and military agencies select certain ones, or why civilians buy a certain type. However it occurred to me that the requirements for military and law enforcement weapons might not be so relevant within the confines of drywall and ranges likely to be within seven yards.
So as far as I can tell, these are the reasons for the popularity of various popular cartridges and my thoughts on them. I'm hoping you guys can straighten me out if I'm off. Also what cartridge do you use for home defense and why?
.25, .380, .38 special etc - The best gun for defense is the one you have, so I appreciate these for their ease of use in concealed carry, but is there any reason to select these sorts of rounds when you could have a full sized gun?
9mm, 5.7 mm -allows for a smaller gun for more comfortable carry without sacrificing high capacity. Also they are supposed have better armor piercing capability, but that's with military rounds as opposed to home defense hollow point variants. Also popular militarily for the lower weight of the rounds compared to a .45. Important when on the march or when you're having to deliver supplies around the world and into the middle of some desert or Jungle backwater, not so much a consideration for home defense.
.40 S&W, .357 Sig -These seem to be getting quite popular, particularly the .40. But the draw for their creation and use by law enforcement seems to come from their external ballistics at range compared to the .45. That is very important if you're going to be in a shootout while taking cover behind your squad car parked down the street from your assailant. But it doesn't seem nearly so relevant to home defense. Maybe if you've got a McMansion. But again I'm not expecting to get a shot beyond seven yards, and never more than 14, which would require me to be twisting around a staircase and them to be in the far corner of a room I could just barely see into from there.
.357 magnum, 10mm- My understanding is that the reason the .357 magnum exists is because law enforcement wanted a handgun that could punch through a car door and still take a guy out. With the slope of my yard I think I'm safe from having a home intruder crash through a wall. So all you may get for the extra recoil and the smaller hole, just turns into burying the round deeper into my wall or my neighbors. I also understand that these rounds have some popularity for being able to take down game or threats at 100 yards. But I wouldn't want to try and explain a 100 yard "defensive" shot to the police.
.45 ACP - nice big deep holes without a lot of flash or much more recoil than 9mm. It seems like the round to choose for home defense, if you've got big enough hands. 45 GAP sounds like it hasn't been so popular for some reason, with only Glock still trying to push it.
.410 bore - With a case that long I'd have though it would have a lot of potential. But everything I've been able to find indicates that you do better with a traditional bullet over the slugs, and the penetration just isn't there with the buckshot or disks, and the spread hurts shot placement. It'll still spoil someone's day, and you are making a number of holes instead of just on, but not what you want to have against a big guy in a heavy coat. I don't know how much difference it makes, but all the penetration tests I know of occurred with some distance to the target, like 25 feet or more. I wonder if things are quite different at 25 inches. Besides not losing speed to the air, you'd think they wouldn't have spread much and the first would weaken tissue and break bones ahead of the rest.
.50 AE - While I could appreciate the raw intimidation of a Desert Eagle, it sounds like this isn't popular due to the flash and recoil one gets compared to the increase in wounding. Also at something like a buck fifty per shot I have concerns about how much I'd practically train. Still though, if my efforts at work and the gym result in a promotion and a grip of iron, might this be a better option than a .45? Or for a given arm strength are you going to still be able to fire more accurately and faster with a .45 and therefore come out ahead?
Big revolver rounds- same problems as the .50AE except in a less convenient form.
Of course those are the things you could put in a handgun. I've been giving thought to the idea that none of the handgun rounds really match up with a full power rifle or shotgun. But handguns are just easier to keep closer at hand, and I think that might be even more important.
Though I'm considering going with a handgun for getting rushed, and a shotgun for "honey, did you hear something?" situations.
Actually that was included with the "etc" for the list of little rounds. 
