Anyone ever seen one or thought about building one?
My featherlight upper is a 14.5" midlength. It’s really hard a reliable gun with a barrel 13.7" or under on a midlength.
My most used carbine is a 14.5 mid length. I’ll defer to others about going shorter as I put reliability over all else.
A few makers have 14.5 with perm hiders with a mid-length gas system. I would think for the shorter barrels that you would be out of tube before you got to the gas port.
Pertaining to perm hiders. What happens when you disassemble the upper? Do you have to leave the FSB on the barrel?
Have a pic of this rifle?
Who offers the 14.5" mid lightweight? Would really like one and don’t know if I can wait for BravoCompany to make theirs… 
Midwest Industries sells the CMMG 14.5", but I would just send a BCM middy to ADCO to cut it down.
Mine started as a 16" stainless RRA 1x8 barrel w/.223 Wylde chamber.
I had it shortened to 14.5" and then just recently had Drew at W.A.R. Rifles (one of my 3gun sponsors) turn it down to .565" barrel profile as a special project/experiment .
“Who offers the 14.5” mid lightweight? Would really like one and don’t know if I can wait for BravoCompany to make theirs… "
Noveske!
They should release their N4 Light barrel in a 14.5" Middy.