#LJamesSullivan

In 2012, AR-15 designer Jim Sullivan applied for a patent for a new rifle design. Apparently based on his Ultimax 100 light machine gun, the rifle features a quick-change barrel, a guide-rail-less receiver with a “backbone” guide rod attached to the lower receiver, a modular trigger pack, and dual firing modes in the open and closed bolt positions.

InRange has an excellent interview (and range video!) with Jim Sullivan, a designer of the AR-15, Ultimax 100, Mini-14, and other firearms. In it, they get to fire Sullivan’s improved M4, which is more tolerant of sustained fire and employs the “constant recoil” principle used in Sullivan’s Ultimax 100 machine gun. I’ve fired the latter weapon, and I can say without a doubt that Sullivan means what he says when talking about its performance and soft-shooting characteristics. To help illustrate this, here’s a video of my friend Arthur firing the Ultimax 100 taken by a high speed camera at about 1,000 frames per second (due to the lighting conditions that evening, the quality is not as high as I would like, but the effect of the constant recoil mechanism is very evident):