For me, I carry the same gun for a length of time, usually 4-6 month stretches.  I do change guns but there's a long time inbetween those changes.  That's mostly because the rest of the firearms are in the safe and I don't take the time to swap them out.

The most complicated manual of arms handgun I carry is a 1911.  Oh the humanity! That thumb safety will get you killed!  Next most complicated is an HK P7.  A squeeze cocker!  You'll never remember to grip it hard enough!  Last is a Kahr P9.  That long trigger pull and reset will slow you down so much the bad guy will shoot you before you get a shot off!


Seriously, I don't worry about it as the manual of arms and ergonomics are so close on most guns as to make no difference.  I've practiced and used a 1911 so much that my thumb goes right to where the safety should be, and I don't even know when I take the safety off in the draw.

Here is my theory of things like this, or at least how I handle it. Most of my carry guns are 1911's, which have a manual safety and a single action trigger. By that method, they are the most complicated guns in my carry rotation to shoot, because I've got to disengage the safety, then fire. Where things like my PF9 are just point and shoot though with a long trigger pull in that case. And most of my guns follow the same basic functions, though I do have obscure stuff like a Taurus PT145 with a manual safety and a super long trigger pull. None the less my figure is that if I teach myself to disengage the safety or try to before shooting anything it solves the problem. IE If I'm shooting my PF9 under stress I try and reach for a safety, if one isn't present then I of course don't hit anything and still can shoot. Same goes for the majority of my guns, now that said I pretty much never actually do that reach, since most of the time I've got the time between realizing I need to draw my gun and trying to fire to realize "hey I'm shooting my PF9 and I now know the whole of the action and mechanism".

The closest situations I've had are shooting critters when they are running and I've got a window of opportunity to shoot them IE usually squirrels, skunks, etc. In those cases I've used just about every gun in my collection and I've never had a situation where I've had a problem say forgetting to disengage the safety on my 1911's or anything of the sort. Honestly never really noticed the difference in triggers that much on the first round, second etc maybe but it's slight. I think there is something to be said for being familiar with the gun, putting allot of rounds down range and practicing with it that will seriously help to be able to switch platforms.

Also I think there is a personality component to this as well, most guys on this forum are what people would say are pretty serious gun guys. For less serious gun guys it's going to be that much more difficult to switch platforms because they're familiarity with a single firearm is very limited let alone many. As an example I've taken allot of guys shooting over the years, and often times they are far less experiences shooting handguns than they had let on. Sometimes they are blunt and say they don't know this or that or have never shot a handgun. Either way when they say yeah I own a 1911 or carry a 1911 and that's what I shoot. I've seen the same guys struggle to realize why the gun didn't go bang, only to realize the safety is on. This isn't an unfamiliar platform in that sense, but they themselves are gun guys so to speak. They don't spend hours on forums and the range learning the ins and outs of a particular gun before buying it. And they haven't spent hundreds or thousands of hours with that gun in their hands over the years. So those guys are different, and I'm not disparaging them they have other interests and priorities that don't include as heavy of a dose of firearms as I do.

In the same thought there are parts of firearms I'm in that boat, if I'm honest high end collectable shotguns not my thing. Can't afford it and it doesn't strike my interest, as such I know very very little about them. It's just not important to me, the same way handguns and manual of arms for various guns aren't important to them. So there is a personality element in my opinion, and a purpose. If your purpose for say owning a 1911 is to plink at the range, well forgetting about the safety being there on the first round isn't a big deal. If your purpose is carrying that gun for your safety and your family, I think it's prudent to spend more time understanding how it works, and learning to use it well.

Luke

Your results may vary-
 Running a IPSC course for fun (I was never a serious competitor) I had a hard time switching from a P7 to a 1911.  It is not just the squeeze cocker, or the safety on one and not the other, or that one has a slide release on the frame and the other has it built into the squeeze cocker, or the mag button on the side vs on the heel of the grip, or the different feel of the weapon in the hand- but taken all together, it was not a smooth transition at all.

 My take- with all the variability's we cannot control, does it not make sense to eliminate the few we can control?

If you can't walk and chew gum at the same time you should probably forego carrying any firearm at all.        Does you family own more than one kind of vehicle?  Do you drive all of them?  Seems to me that switching from an F-150 to a Harley Davidson Road King is at least as big a difference as switching from one handgun to another.  God forbid that you should climb aboard the John Deere combine and run it down the road to the other field.      

If you can't walk and chew gum at the same time you should probably forego carrying any firearm at all.        Does you family own more than one kind of vehicle?  Do you drive all of them?  Seems to me that switching from an F-150 to a Harley Davidson Road King is at least as big a difference as switching from one handgun to another.  God forbid that you should climb aboard the John Deere combine and run it down the road to the other field.      

  Sounds obvious and simple-
  but I think there are factors you may be missing. A definitive shift from obviously different items (a pickup truck to a motorcycle) will key in a whole different set of responses.  But from one car to another, or one motorcycle to another, yes, there can be problems and there has been an effort to standardize controls. - for example, left side shifting was made mandatory on bikes. Go ride that Harley and then jump on a 60's brit bike and see if that right side, one up, three down shift pattern and left side brake does not give a bit of confusion.
  Most modern cars have controls much like each other, designed that way for a reason.  Power, prop and carb heat share distinctive odd shaped knobs for identification across many different aircraft.   
 
 I am not talking about a range trip here, but an encounter that is going to involve a massive stress load. People don't work smooth under stress. Even simple things get difficult. I never had the slightest bit of trouble running that P7 and 1911 at the range- only when the time stress of competition was introduced did the problems show up. And they were not huge-half a second wondering why the mag would not drop, but when under attack it would have been a big deal.
 There is going to be a familiarization time with any new object- so once a year switching guns is probably not too bad,as that time overall is relatively low- but switching out on a day to day basis makes the adjustment time ever present.
  The counter argument is people are so familiar with their firearms they do not need an adjustment period-
 add stress to that, and things can change.  One reason old guys are conservative (not in a political sense) is that we have seen how many flavors of mistakes there are.

I'm with Armoredman.  No external safeties in use on any of my carry guns.  The only one with an external safety (not currently in rotation) is a Ruger SR9c, and when carried will be carried with the safety off.  And that's not any more dangerous than a Glock.  The only differences between them all are capacity and how the reload works.

   I switch carry guns to a point.      All of my stuff is DA/SA however with the exception of my 1911.  So same basic function.

    As someone who uses and carries a lot of guns at various times, I'm not worried about changover.   Casual shooters, or people who are "gun people" but carry a different one every day, yet never get range time?   Yes, I believe that could be a problem.

 

I typically carry non-external safety guns: revolvers, Glock, Sig Sauer, etc.

I like Clint Smith's philosophy, though. Perhaps carrying multiple guns, as long as one is familiar with them, is part of becoming accustomed to multiple weapons systems?

I know the argument has typically been against safety, but maybe familiarising one's self with multiple platforms enhances safety? Even in the hand, without looking, there is night and day difference between the feel and balance of my handguns.

I'm not sure Mr. Smith is advocating carrying multiple types so much as advocating familiarizing yourself with them in case you are presented with a situation requiring their use.  I carry a Lightweight Commander 9mm, but I sometimes rent other types at the range such as a Glock 17 or a Sig, whatever -- just to get some trigger and handling time with them.  But I focus on training with my carry gun or one very much like it.

But I am not an expert and I'm simply explaining what works best for me.

I would agree up to a point but what you are describing is more a lack of general proficiency than the idea that you can't successfully switch from one manual of arms to another when the chips are down.  I have been carrying and using S&W double action revolvers and 1911 pattern pistols for the better part of the last forty years as well as bolt and lever action rifles and various shotguns both in the field after game and as personal defense weapons.  You may outdraw me and you may outshoot me but it isn't because I lack the proficiency to operate the weapon or the presence of mind to know the business at hand.

I guess that's the thing:    I think only in two instances would someone ever "become dead" over changing a manual of arms.
#1.  A new shooter or low-round-count shooter who doesn't practice enough.
#2. A non-gun person such as a experienced/good Police officer, or a person who has championed his whole to being a one-gun shooter to become super proficient.     They've spent their whole life with ONE handgun.

    Other than that, I believe what minor slowdowns there are in say pulling a striker fire trigger instead of a DA/SA, are NOT factors or times/speeds large enough to cause a gunfight to go the wrong way.

   

I would agree up to a point but what you are describing is more a lack of general proficiency than the idea that you can't successfully switch from one manual of arms to another when the chips are down.  I have been carrying and using S&W double action revolvers and 1911 pattern pistols for the better part of the last forty years as well as bolt and lever action rifles and various shotguns both in the field after game and as personal defense weapons.  You may outdraw me and you may outshoot me but it isn't because I lack the proficiency to operate the weapon or the presence of mind to know the business at hand.
I think it is pretty obvious and it is fairly simple.  While it is true that none of us may operate in the manner we hoped for in an emergency, we are all the culmination of or experiences at the moment of truth.  We do our best and let the chips fall where they may.

 I chose the analogy of operating a motorized vehicle on a public highway because that is one thing that nearly all of us do nearly every day that puts us in a potentially life threatening circumstance with other people who are similarly equipped.  A potential accident situation can develop very, very quickly and usually without much warning.  As in a personal defense scenario, situational awareness is the key and proficiency - yes, even expertise may be the difference between surviving the situation and not doing so.  Experience and judgement are also things we all possess to varying degrees and will factor into the outcome as well.  You may be licensed and insured for the operation of everything from a moped to a tandem trailer eighteen wheeler and you are expected to do so in a manner that does not endanger yourself or others on the public streets and highways.  The fact that we, for the most part, are able to do so argues in favor of the ability to master more than one system.  I am personally acquainted with two pilots who simultaneously maintain both fixed wing and rotary wing ratings.   

I agree that situational stress is a complicating factor but as I said before, experience and judgement are going to play their part as well.  I don't go armed and in harm's way as a profession but if I did I would be expected to be proficient with both handguns and long arms as well as my chosen back-up weapon in the course of my duties. Simplifying the process can help to a degree but I still maintain that if you are not capable of proficiency you may be in the wrong line of work.  There are, in fact, people who should not carry firearms or even sharp objects on their person.  I may be one of them someday but thankfully today is not that day. 

For the record, the F -150, the Harley Davidson, the John Deere combine, a GMC two ton truck with a split axle, two different farm tractors, various and sundry implements from plows and cultivators to planters and mowing equipment, were all things I was simultaneously proficient at operating.  Later I added a Triumph motorcycle, a backhoe and end loader, and a second pick-up truck with a three speed column shift.  All  were driven regularly or required to be moved on public highways between two farms in the area.  I am not bragging - simply pointing out that although the controls were different the operating principles remained the same.  Shiny side up - keep it between the ditches - don't run into things. 

I can't say what works or doesn't work for you, only how I approach the situation.

 
  It is not the diversity of machinery, but the similarity that I see as a disadvantage.  No one will confuse a combine with a car.  Nor the collective with a yoke. But one might be disoriented under stress between two things very similar, yet different in operation.  Each to their own.