When i was a DS i bought 4mag. insted of the requied 3. I keep them in rotation every week. And most of the time I keep the 2 extra ones on my belt missin one round "IE 14 rounds insted of 15" the one in the gun was fully loaded. --I have read that Jeff Cooper "G@A" shot a fully loaded 1911 with the same ammo in it sence WWII with out a malfuction. I have shot one of my uncles 9mm that was brought back from WWII it had been fully loaded sence he returend home it fouction fine.I have only had two mag. malfuction one was on a old 20ga bolt action shot gun and on a cheap mag for a 30cal. Ibelive that a good qulity "factory mag" is less likely to fail than a cheper stilled aftermarket one. For a pesonal defence of duty gun i would use factory mag. and for my pice of mind replace them about every 5years with new factory mag.