Ammo problems, short story and need advice on how to avoid it in the future.

So I've been carrying a couple of years now and when I started this I went hard into whatever research I could find. This led me to using Winchester Train and Defends for my 3" barreled 9mm's, and I used the same for my Compact sized as well.When I got them just over a year ago, I ran a few magazines through my shield of the defends, did some more trains, all was ok. I also got a great deal on blazer brass for practice and bought a ton of it. I've been shooting it flawlessly for the last year and a half out of all my guns.I also neglected using my actual defense ammo, due to cost and availability. Trying to find T&D's online is a waste of time. Its actually easier to find it physically in a store than online.Fast forward to yesterday. I realized I've been bad neglecting my defensive ammo, and decide to run a box just to make sure I'm good.First up is the shield 9mm which I never had a problem with for close to 2000 rounds. I get a failure to eject after 4 rounds in the 7 round mag. ... Shit..... Had to rip out the mag (which is a pain on the 7 round) to clear, as the partial ejection had lead to what looked like a double feed.Ok well lets try my Sig p320c, I NEVER had a single issue with this one. About round 10, exact same thing as the shield, FTE and type 3 malfunction again.I did have about 200 rounds of the Winchester Trains (same weight, shape, load) as the defends and THOSE were fine in both guns.Now I'm having a major concern about the ammo or at least how I handled it. Being I have only the standard 2 mags for the shield and p320c, and I make relatively frequent range trips, my usual thing to do is unload the mag from the defend ammo, fill it with blazer, and the reload the defend when I'm done. I have no idea how many times I did this but lets say at least a couple of dozen. My wife does the same though she doesn't shoot as often as me.I wanted to do more testing but I've got only one box of defends left and as I stated they are a pain to find. My local bass pro has them for all calibers in stock, but 9mm.So I'm looking for recommendations.Buy extra mags for the guns, and keep one "defensive only"? The only issue with this is there will always be some cycling.Put a "lifespan" on my carry ammo of some number of months?Not sure but that really shook my confidence in my guns going boom when they should. via /r/CCW http://ift.tt/2lYNy6O