Ok, your comment about golf carts and numbers of specialized bullets, leads me to make a comment.
My first trail handgun, was a 357 Mag double action revolver (Taurus). When I go hunting, camping, backpacking, remote-whatever, I like to take it or a Ruger 357 with me.
The reason I got the 357 Mag DA was so that I could load the cylinder with a couple of 38 specials, a couple of 38 Shotshells, and a couple of high performance 357 Mags; put it in my holster and know that I had a quickly available firearm for just about anything (small game for a camp dinner, kill a snake, scare off something, personal protection.) All I needed to do was rotate the cylinder to what was required.
I also carried a shirt pocket cartridge wallet with more ammo.
Therefore, there are easier systems that don't involve gold carts.
The same could be done with different magazines for a semi-auto, althought that is a bit more hassel.