So, this really wouldn't have worked as a poll, nor did I want it to be one. I've really been enjoying this section lately as there's been some good content backed up by experience. To the Topic: On a Practical Level. . . How do YOU determine what length gas system YOU will use on your (X") barreled upper? Why? I know the basic "Normal" or "ideal" set ups that all have close to the same dwell time: 14.5" = carbine length 16" = mid length 20" = rifle length OK, that's a good gauge, but I kinda like the way my 14.5" middy shoots. What about an 18" barrel? Mid or rifle? Let's hear it!