check your gas key/tube fit. also make sure your gas block is seated right over the gas port.
i have one bcg with a tight gas key and it binds up like that on several tubes, but does fine on one ,so i dedicated them to each other.

Last edited by deerstalker; 10/01/16.
the consolidation of the states into one vast republic, sure to be aggressive abroad and despotic at home, will be the certain precursor of that ruin which has overwhelmed all those that have preceded. Robert E Lee
~Molɔ̀ːn Labé Skýla~