I have been using Springer Precison FASTMAG PMAG Couplers for several years now and have arrived at the opinion that they are easily the best magazine couplers I have used. Certainly there are less expensive options but none of them offer the secondary benefits that the FASTMAGs offer.
The reasons for using something like a magazine coupler on a home defense carbine are two-fold for me. Having additional capacity is certainly one of the reasons but there is one reason that is often lost in discussions like these – dealing with malfunctions. It has been said that most malfunctions are magazine related. I can’t back that up with science but I have found that to be true in my experience. A coupler gives me the ability to reload or switch to a new magazine during a malfunction clearance.
The Springer Precision FASTMAG does three things better than other magazine couplers. First, it has the least overall effect on the handling of the magazines. The front of the coupler has a cutout that conforms to the shape of the PMAGs. This allows the user to grip the magazine with a strong and completely uninterrupted “beer can” grip during a reload or while stripping a magazine. Most couplers strap the magazines around the middle which interrupts the grip.
Second, the FASTMAG places the magazines at the same level instead of staggering them which makes them act as a very stable base for prone shooting, more compact overall, and easier to handle. In my experience, this has not been the malfunction causing boogie man that it is made out to be. In fact, it has been a complete non-issue with more benefits than downsides. I start with the spare mag on the bolt release side of the AR so the ejection port is not obstructed when it opens at the first shot. Even if the mag is on the ejection port side, it can open enough that is typically won’t cause a malfunction. If it does become a problem (it NEVER has for me), the mag can be slightly flexed out of the way allowing the port cover to fully drop.
Finally, these have the easiest installation of any coupler I have tried. They install the same way PMAG base plates install – push button to slide off base plate, slide on coupler, reverse to remove. If can be done without tools in just seconds which means you can add or remove them easily as needed.
If you are looking for a functional and easy-to-live-with way to keep a spare magazine on your carbine, check out the FASTMAG Magazine Couplers from Springer Precision. These machined aluminum couplers are available for several different types of magazines and some even increase capacity.