Just got my MPX carbine and only had one opportunity to get to the range and sight it in. It would not run reliably with my 130PF loads, one out of every 5 would not eject or would short cycle the bolt. I think they need a break in period. I also tried a load of 4.0gr Tightgroup with a 124gr JHP, much better! Cases eject about 6-8 ft., accuracy at 25 yds was acceptable. Since the range I was at will not let you shoot fast, I don't know how the load will work under match conditions. That test will be at a different range. My MPX also likes lots of lube, runs smoother.