The concept of modular firearms is gaining a toehold in the shooting world. For some, the idea of having multiple calibers based off one platform has plenty of tactical and practical allure.
Colt is among the companies that have embraced the notion with its M.A.R.C. 901 series. The Connecticut manufacturer's three models of Modular AR Carbines are sold as AR-10-style rifles, which shoot the hard-hitting 7.62x51mm NATO/.308 Win. round. But they can be switched over, lickity-split, to any AR-15 caliber.
In addition to thumbing off rounds in the above video, Hickok45 also demonstrates exactly how simple the caliber conversion process is on one of the M.A.R.C. Models. In this case it's a Colt LE 901 16S. While it’s not a procedure that can be done on the fly, it’s a simple one, requiring little material and absolutely no tools — save a bullet to push out the retention pins.
The M.A.R.C. 901 is an intriguing series of rifles and it’s a fairly safe bet shooters will see the modular concept continues to be applied as the years go on.