You lucky dog, I absolutely love the 4500, 1006, 5906 series. I have 12 variations of the 4500 series, 9 of the 1006, and 14 5906's. They are brutes. I was lucky enough to buy the entire magazine inventory of a gun show dealer going out of business. Ended up with hundreds of magazines Ifor each of my semi's. The others are vacuum sealed until I need em. Keep it, shoot the frijoles out of it and enjoy it. Now, I have 2 of the older 645's, one of which is nearing the 80k round mark. New spring changes 3 times, still as pristine as day one. Admittedly, not competition grade accurate, but the worse of my lot gives me 3.02" groups at 31ft, the best gives me 2.15" at 31ft. My 1006 series and 5906 series eat anything, my 4500 series seem to prefer IMI and Winchester brown box service grade the most. They WILL shoot anything, but prefer those two. The ONLY issues I ever had with any of them came when I used promag magazins I got in my dealers 1 buck bin. But then, you replace those springs and followers with quality mag rebuild kits you get good mags.