It makes me wonder a lot about using those special high end bullets that everyone puts in their gun for carry but never get around to shooting so they can "save" them or just because they are so expensive...
Here's what I do. When I choose a new defensive ammo, I bite the bullet (so to speak) and fire in excess of 50 rounds, closer to 100, through any magazine I plan on carrying, so I have confidence that it will feed reliably and hit to point of aim. Then I practice with ball ammo that is the same weight and velocity so that the felt recoil is close enough that I can't feel the difference. I then make sure and fire through the carry stuff at least once a year and get new carry ammo.
Costs a little, but pays great dividends in peace of mind knowing that the ammo should never be an issue and I know exactly what to expect from it.