
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.
Get On Target
Why You Can Trust Gun Digest
Since 1944, Gun Digest has been a trusted authority on firearms, shooting and shooting gear, delivering expert firearms reviews backed by nearly a century of experience. We go beyond standard reviews, combining hands-on independent gun testing, in-depth research, and expert insights from industry professionals and manufacturers.
Our reviewers are the bedrock of our testing and come from a comprehensive cross section of the shooting world. Their diverse backgrounds include law enforcement professionals, military veterans, competitive shooters, seasoned hunters and life-long firearms enthusiasts. In addition to being firearm experts, we are also thorough journalists adhering to the strictest standards of the profession.
For our readers, this means objective, unbiased reviews, free from outside influence. Our priority is to provide the information you need to make informed decisions—whether a firearm or piece of gear is a must-have investment or one to pass on.
Find out more about our Editorial Standards and Evaluation Process