I cringe when I hear some defensive shooters talk about their "carry rotation" and the different guns that they switch between on a regular basis. I remember my friend Sheriff Bill Cooksey, who was called out on his day off to check on a suspicious person. Instead of strapping on his .357 Mag, which he carried on his right hip, he chose to just stuff a semi-automatic pistol into his waistband on the left side, crossdraw style. That suspicious person pulled a gun on the sheriff and started shooting. Out of habit, the sheriff reached for his right hip instead of going for the gun stuck in his waistband on the left side. As he finally got the semi-auto out and was fumbling with the safety, my lawman friend was shot twice and very nearly died from it. We develop habits whether we realize it or not.
Still, there are times when a person needs to change guns or carry locations. We might be going from winter carry to summer carry and need a different gun and different carry method. Our primary defense gun might be in the shop, and we are making do with another gun. Or, we might just have found that we shoot a different type of gun better and are planning to start carrying it for personal defense. There are a number of legitimate reasons to switch guns other than just trying to be cool and impress others with our assortment of handguns. I would suggest, however, that there are some things that we might do, prior to making the change.
The first step would be to make sure that the replacement gun is in good working order. Take the time to field strip it, clean, and lubricate it. This would also be a good time to check the various safeties to make sure that they are functioning properly. Making sure that you have fresh ammunition for the gun and your load out would be a good idea, too.
Following the cleaning and inspection, it is a good idea to do some dry practice with the gun including a number of presentations from the holster. Having a supply of dummy rounds will also allow one to practice the speed loads and tactical loads. And, finally, some live fire sessions at the local range would be a great idea.
While all of this might seem like going to a lot of trouble just to switch guns, you have made sure that this replacement gun is serviceable and you have created habits in the handling of it. Since we are all different, some will have to spend more time in these practice sessions than will others. Just take whatever time you need and make sure that you have created the kind of habits that will serve you in a defensive situation.