I know what it is like, to find that a carry gun’s mag has been released. In the several times I experienced this, the mag was always still mostly or partly within the mag well, but, the lesson was/is that a magazine could be lost. So, unless the auto-pistol is a Seecamp, one spare mag is my minimum. (It is actually difficult to get a mag out of a Seecamp pistol, intentionally.) I did remedy those unintended mag drops. In one pistol’s case, I learned to use better holsters, that could not flex, in a way that pushed the mag release button. (Compact 1911) In the other case, I stopped using that pistol as a duty handgun, because it was the fabric of the patrol car seat that was snagging the heel-clip mag release. (Older-type SIG P220, with heel-clip mag release. I reverted to using a duty revolver, then, later, used duty autos with push-button mag releases.)
Another reason for me to carry a second mag, is so that another will be there, in case I execute a malfunction clearance that includes stripping the mag. Even if my intention is to retain the stripped mag, funny things can happen, during extreme stress.
If my carry gun is a revolving pistol, my usual minimum spare ammo is two Slow Strips, each holding four cartridges. I may “store” more cartridges in more-fully-loaded strips, but my go-to strips are loaded with four, each, with space between the pairs, to expedite getting two to four rounds into the cylinder as quickly as smoothly as possible. (My way is not the only way, of course.)
It is normal for me to carry secondary and tertiary weapons, especially if “primary” is a five-shot revolving pistol. (”Primary” might be an SP101, while “Secondary” might a Glock, due to my aging right hand’s gripping capability doing best with smaller-gripped weapons.)
If carrying a K-Frame or larger revolver, I may well carry two speed-loaders, and just one strip. K-Frame, and larger revolvers, offer more work space to efficiently use speed loaders, than do the smaller weapons.
If one of my weapons is a Seecamp pistol, it is almost never the ONLY weapon.
Edited to add: I am retired from policin’, so, being “subject to duty” 24/7 is no longer a factor. Violent crime is, most certainly, up, in my part of this metro area, so, what I carry is evolving, and, I will vary, what I carry, depending upon my planned routes and destinations.
