I finally got my 9MM MP5SD out of ATF jail and took it to the range. The first two boxes I ran were 147 grain Winchester and the gun ran perfectly. I changed to 115 grain and after the first couple of rounds, it would fail to eject the casing. Clear it, and the second new round would FTE. I assumed it was just running hot so I let it cool and came back to it. Same problem, different magazine same rounds ran fine through the SP5K. Went back to the 147 grain and it spun like a top. Any one had this problem before?