In the spirit of two earlier articles I posted on sport shooting and accessory/part selection, I wanted to share some lessons I've learned the hard way (not the "Oh crap, I'm going to die" hard way, just the "Hey, something's not right and I spent money on this" hard way).
I own a CZ-85B that I had customized specifically for sport shooting. As part of the custom work, I had a trigger job done that resulted in an amazing improvement in the crispness of the trigger and the pull weight reduction. When I went to test fire it in the middle of the ammo shortage, I had a mix of PRVI and PMC ammo to run through it. The PMC ran reliably throughout, but I experienced several failures to fire with the PRVI. I took the ejected rounds and ran them through my other 9mm I had brought (unmodified), and they fired. I was a little confused at first, because my CZ had always run whatever ammo I fed it previously. Then I decided to read the description of the work that had been done to it. Included in the trigger job was a lighter mainspring. One of the things your mainspring influences (other than trigger weight) is how hard the hammer strikes the firing pin. A lighter mainspring means a lighter hammer strike. Ammo with harder primers (PRVI, TulAmmo, etc) may not reliably fire in a gun with a lighter mainspring.
Does this concern me? As it relates to my CZ, no. As I stated, I wanted this gun modified specifically for sport shooting. When I sport shoot, I control the ammunition that I feed it. I'm not quite to reloading yet, but I can try multiple types of ammo, and feed it the one it likes best. For those of you who are planning for the Day of the Zombie Horde or other self-defense/societal breakdown scenario, this should concern you. Unless you have cases of ammo stacked in your garage (and judging from the shelves at Wal-Mart, some of you do), there will come a point when you will need to scavenge for ammo. When that happens, you need a gun that will reliably fire whatever you can find. Gun designers are relatively smart people, and they design guns to perform in a variety of scenarios. If you choose to tune your gun for a specific purpose, that is perfectly fine, but be aware of the unintended consequences that may come of it.
In summary, it's your gun, tune it the way you want, but ensure that you have done your research and understand any unintended consequences that may occur. Just because it’s the latest and greatest, or the manufacturer promises that this is the last upgrade you’ll ever need, or your buddy tells you how much faster he is with his super-light trigger pull doesn’t necessarily make that set-up right for your intended use.