Check the gas block, if I remember right someone on here measured the gas port location and without the hand guard piece and was ok to install flush without a space. I measured my low profile gas block and the hole was large enough to be install flush. If the gas block checks out just keep shooting it and lubing it, mine would short cycle when I first got it. Now after about 300 rounds thru it I don't have any issues no matter what I put in it.