One of the best things about AR-15s is the ability to quickly customize the configuration for different duties—whether it’s home-defense, punching paper at long distance or staying up with the pros at the next competition. That’s also one of the biggest drawbacks. Toss on enough gear and it’s not long until it handles like an overweight luxury car lumbering around a curvy race course.
That fact and budget are the main reasons I’ve been slow and deliberate in changes to my SIG Sauer M400 Classic, although it looks like the Mission First Tactical Battlelink Utility Stock (BUS) is destined to become a permanent fixture. Don’t get me wrong. There’s nothing wrong with the adjustable length-of-pull stock that comes with the SIG. In fact, it’s so positive and comfortable that it’s taken me four years to even consider a swap.
The BUS has some good things going for it, but first the bad news. The stock that comes with the M400 weighs 8.46 ozs. The Mission First Tactical aftermarket unit tips the scales at 9.54 ozs., even without the rattle-deadening foam provided for the battery compartment. The company lists the unit at 8.75 ozs., although regardless of the figure you believe, there’s no denying ounces can add up to pounds.
Construction is thick and rugged to shrug off those errant bangs, which partially explains that extra ounce. It’s also 1.25" longer (8" measured along the top). That changes the firearm’s overall lengths to 33 5/8" (compressed) and 37" (extended). The original configuration figures are 32 3/8" and 35 3/4", respectively. My figures don’t quite agree with SIG’s specs, either, but there’s no debate overall length increases. The change isn’t much of a concern in my case, now that the eldest three shooting addicts for grandkids have grown tall, lanky and joined the U.S. Army. I’ll save the standard version, just in case the youngest one in second grade becomes another range rat.
The BUS is 1.75" wide, compared to the original’s 1.46". The difference seems minor, but it and the gentler taper provide a much more comfortable cheek weld. At the bottom of the buttpad, which is a slightly soft but not tacky substance, it’s squared, with 1.15" of flat surface, which keeps things from rolling as much at the bench. A slight angle from the toe to the top of the buttpad is designed to speed presentation.
At the bottom, you’ll also find a roll pin, which serves as the hinge when opening the waterproof compartment that stores up to six CR123 batteries. That’s a lot of room, and the foam inserts are a welcome touch to minimize rattling. To open, a pair of smartly recessed buttons at the top of the buttpad are squeezed simultaneously while rotating out and down.
This thing isn’t coming open accidentally, take my word of it. In fact, even when you adjust length of pull the stock snaps in position with confidence-building authority.
The unit comes with a pair of quick-detach sling mounting points (both sides) and one standard version. It works with mil-spec, six-position buffer tubes and is available in a commercial-spec version.
There’s no denying the AR-15 is one of the most versatile and customizable firearms available today. It can be a blessing, or curse, depending on the changes you make. I have future plans for that spacious storage area…..hopefully it won’t take me another four years to get around to them.