I picked up some of the Winchester Train & Defend Training ammo on clearance at Walmart and now I'm wondering if I made a bad decision. I didn't notice until I got home that it used lead free primers. Now I'm second guessing myself. I've read that lead free primers have a limited lifespan, but the opinions I'm seeing of how long they will last seem to vary. Do any of you all have personal experience with it? I bought enough in calibers that I don't shoot all of that often that it should last me quite a few years. I'm going to try to shoot it first when I take those guns to the range, to shoot this up, but I'm wondering how long I have? I also don't know how long it's been on the shelf at Walmart.