Originally Posted by Quentin
Keeps the screws tight that secure the gas key. You get short stroking if the key loosens. If it gets real bad the key and gas tube can self destruct upon impact.
More than likely though, you will just end up with what basically amounts to a bolt action rifle, with a little lower velocity because the gas that would have gone into cycling your bcg to lock your hammer to the rear is just going out the side of your gas key. Not dangerous most of the time, but aggravating as hell. When I was in BNCOC in 2006, the cadre disabled the gas system of our M16's so we had to pull the charging handle back every time, and Soldiers who were used to qualifying sharpshooter and expert every time were ending up barely qualifying or bolo. One of our instructors was a POW in 2003, and he said that because of the sand and not being fielded cleaning kits, that is what happened to them. Their weapons wouldn't cycle, and they had to manually charge the weapon each round.