Not only could you share ammunition and magazines with, say, your Glock 22, by swapping the modular magazine housing you could do the same with a Smith & Wesson M&P40. This carbine also lets you move the operating handle and the ejection port to either side. Unlike an AR, this lets you operate the action with your left hand while it is still on your right shoulder or vice-versa.
Winchester's 155-grain Silvertip bullets were 250 fps faster through the carbine than through a pistol.
The JR Carbine I tested was a pre-production sample. I don't usually write up pre-production guns, but I needed a carbine in .40 S&W for testing and this is a unique design that emulates an AR to some degree. Its versatility was applauded by all who fired it, but feeding problems with hollow-point bullets plagued the gun. FMJ-style bullets fed just fine. The JR Carbine is shipped without sights, but it has a 15-inch Picatinny rail atop the receiver and fore-end. When and if the reliability issues of this distinctive carbine are sorted out—engineers at EMF assured me they are working on this—it looks to be an affordable and viable pistol-caliber carbine.