Originally Posted by
MistWolf
Before opening the gas port, check the hole alignment between the gas block and the barrel.
i recently had an issue with a 10.5" barrel with an .082" gas port and an adjustable gas block. With the handguard cap and adjustable gas block, the shorty wouldn't function. Without the cap, it would barely function. After taking a few measurements, it was determined that the gas port on the barrel was located .275" from the shoulder on the barrel and the hole in the gas block was located at .308", a difference of .030". I had to sand down the gas block to get the holes to line up correctly