What is the length, in inches, of carbine, mid, and rifle length gas tubes?
Stumped the band, huh?
I have a gas tube on hand that is 11.7" in length overall - 11.1" from receiver end to gas port.
The packing slip says it is mid-length. Of the two references I can find on the net for mid-length tubes, one says the overall length should be 9", the other says it should be 9.8" to the gas port.
Those numbers neither agree with each other nor match what I have on hand. 
I’ve never actually measured one, but the figures I’ve always seen for the three different gas systems are 7", 9" and 12" respectively.
Hope that helps.
Derek
Sounds like a midlength to me. If I had to guess, the 9" and 9.8" numbers are probably somebody measuring the section exposed between the reciever and gas block, and from the receiver forward to the gas port, respectively. Adding 9.8" plus the protrusion into the reciever, would probably put it dang close to 11.1". At any rate it’s definitely too long for a carbine and not long enough for a rifle.
I’ve got my upper apart right now, I can measure mine when I get home if somebody doesn’t get you a better answer by then.
Your references are for a carbine length gas system. Carbine gas tubes are ~9.8" long. What you have is indeed a middy tube.
I measured my 14.5" carbine LMT upper about 2 minutes ago.