The term "Mid-Length Barrel" is actually a misnomer because the barrel length is actually the same. What it simply means is that the barrel uses a "mid-length gas tube" of 11.25 inches long. Typically, the standard carbine has a gas tube length of 9.75 inches. This gas tube length of 9.75 inches is the one used for barrels 10.5-inch, 11.5-inch, 14.5-inch up to 16-inches.
The relatively new concept of mid-length gas tube (11.25 inches) was designed for and usually installed on a 16-inch barrel can also be adopted on a 14.5-inch barrel. A 16-inch barrel using a mid-length gas tube means that the placement of the drilled gas port in the barrel will be at 7 inches measured from the tip of the muzzle of the rifle instead of the standard specification of 8.5 inches from the muzzle tip. For the 14.5-inch barrel, it will be anywhere from 5.5 to 6.0 inches from the muzzle tip, depending on your choice. The effect is that there will be a little bit less gas pressure being rammed back into the BCG gas key. The use of a mid-length gas tube on a 16-inch or 14.5 inch barrel will render a slightly “softer” shooting, less recoil and less muzzle rise AR rifle.
Since UDMC produces its own barrels from cylindrical blanks, we are now able to introduce this new S5-DGIS Mid-Length model on a 14.5 and 16-inch barrels. Actually, we can drill the gas port in wherever part of the length of the barrel, something that AR assemblers cannot accomplish for you unless they “weld” the originally-drilled gas port which will eventually give way in no time at all.
The only drawback if you order from us this Mid-Length Barreled S5-DGIS is that it will be more expensive. Why? It’s because we will have to install a longer handguard since we will not be able to use the standard M4-length handguard. The handguard that we will install will be a T6 aluminum “KeyMod railguard” that will float the barrel, a feature that a purist competitive shooter wants as it aids in better accuracy. As another option, the KeyMod railguard can cover or not cover the gas block front sights. If you want the gas block inside the railguard, we will install a “low-profile” gas block that will fit inside the railguard. That will also mean a longer railguard to cover the gas block. For the latter design, we will install our own UDMC-fabricated set of flip-up sights for the front and rear.
At the end of the day, the CHOICE is yours. At UDMC, we do our best to please you. In the picture below is a 16-inch barreled F5-DGIS. It looks like a 14.5-inch barrel, isn't it?