I guess if the single use of a handgun is for defensive shooting then a single use ammo is appropriate. I don't agree that one must practice with the same ammo they carry for serious work. If it is reliable, reasonably accurate and shoots reasonably close to the point of aim there is no reason one can't practice with cheap ammo and save the high dollar stuff of serious use. I also don't see any need to "change out" or rotate ammo. Modern ammo will be as reliable in 50 years as the day it rolled off the production line.
I would agree will all said here with the exception of 50 year old ammo.
As joe said, practice with cheap LIGHT LOADED ammo, and when finished practicing put the good stuff back in. How does that work? Works real good if you shoot a lot, and a bad guy tries to take you out. TWICE! I practiced what I had trained for, and didn't have to think about it.
Frangible ammo. All I can think of is.
. 45acp ball will not reliably penetrate a car windshield. 9mm will. 357 mag will out perform both those rounds. There has been much experimenting and AMMO SELLING to L.E. over the years, and all kinda majic bullets, and I was part of that EXPERIMENTING for 20 years. The bullet boys were always sellin dept's the latest bad guy downer. In the end, seldom did it come to anything. Hollow Points work thru hydraulics, i.e. body fluids. If they stop up going thru clothing, and don't work, well now your shootin ball. Oh, but Dee! The new computer designed bullets are much better. Yea Right! Put a hole in the guy and see if he falls. If he doesn't, put another one in him. That's what works.
I was in several situations where guns were involved. Two of which got real interestin real quick, and I was the guest of honor at both. The first occasion I was usin a 357 mag, and the second occasion a 45acp. After the second occasion, I went back to the 357 mag. THE NEXT DAY! And no, the 357 Sig AIN'T THE SAME.
Well. I'm sure I didn't help, but I do agree with joe on his points. All except that 50 year deal.