Assuming you are not limp-wresting the gun, the good news is it is very likely just the fact that it wasn't cleaned first, and a bit of running-in of the parts. The LEM conversion would have nothing to do with it.
Most of my HK's have faired well on the first trip to the range, after initial degreasing and oiling. I've had one that was tight and had 3-4 ejection issues in the first 100-150 rounds, but it has run fine since.
Clean it, shoot it, and don't change any other variable (i.e., use the same ammo). My expectation is after a couple hundred rounds the FTFs and FTEs will go away. If not, you'll get more suggestions here. And of course, you can also get HK Customer Service to check it out if you still have any doubts.
Most of my HK's have faired well on the first trip to the range, after initial degreasing and oiling. I've had one that was tight and had 3-4 ejection issues in the first 100-150 rounds, but it has run fine since.
Clean it, shoot it, and don't change any other variable (i.e., use the same ammo). My expectation is after a couple hundred rounds the FTFs and FTEs will go away. If not, you'll get more suggestions here. And of course, you can also get HK Customer Service to check it out if you still have any doubts.