The threaded rods are standard M3x0.5 like the original build documentation states. I can also confirm as I recently upgraded my 300blk out build not long ago. They tried to make it as compatible with the original build as possible. An interference fit is a good fit lol

I had to open mine up a bit. But I used it to my advantage, I put a slight bevel on that hard lip on the gas block shelf. Then I filed the front receiver opening until the barrel just barely slips in a few mm. Then I press the barrel in the same time I pressed the gas tube sleeve in place. I assumed the tight fit would help with accuracy but I cant prove that. Do your threaded rods fit in without modification? It might be a flow calibration issue.