Besides availability of forends, barrel length, and the fact that not all manufacturers makes middies. For example, since BCM makes a 16" carbine and a 16" middy, would there be any reason to get the carbine over the middy besides the reason listed above?
are we talking about 16" guns exclusively? mid-length in a 16, carbine in a 14.5… every time. there is something to be said for more pressure, however… its my opinion that the longer hang-time you’ve got, the longer a weapon will go before failure from loob burn-off and/or fouling. if you’re not running your gun for 800, 900, 1000 rounds per session without reloobing, this isn’t going to factor in. and why would you?
no- in the end, the longer the hang time, the more beat up your guns gonna get. it’s pretty much unnecessarily harsh, considering we now have middies and even “intermediates” for 18s and so forth. i only pointed it out as food for thought, based on your original question.
i have one 16" barrel, and it’s a middy. i wouldn’t get a 16 with a carbine system.
Comparing two identically setup rigs, once middie and one CAR, with the same type of HG but to the appropiate length for the system, the middie will be a little bit heavier.
In my opinon 16" guns should be middies, 10.5 to 14.5 are the only reason to have CAR systems, and even the 14.5s are available with mid-length systems now.