As part of Sig’s Freedom Days event at the Ben Avery Shooting Center outside of Phoenix, Arizona, the company had its MCX Spear and prototype XM250 light machine gun on display and available for attendees to shoot.
Jason St. John, a well-mustachioed retired Army Ranger and now Sig's director for government products, took a break from holding class on the systems and gave us the 411 in the above three-minute video.
Some of the key takeaways:
The MCX Spear/XM5 has a low-profile buttstock that is both extendible and side-folding, providing soldiers a more compact firearm while riding in vehicles and aircraft. Nonetheless, it is still fully deployable with the stock folded. Attached with T27 Torx screws, it can be replaced with other stocks, and Sig has flavors including one with a gas mask cut and a six-way adjustable precision rifle stock. Alternatively, an M4-style tube can be fitted.
It is closer in size to a compact AR-10/SR-25 rather than an M4. St. John explained it as "an AR-10 version of the M4 version of the MCX," in talking about the upscale. "There's no way to go to a medium-caliber solution without moving up from a small-caliber rifle...you're not going to get the performance from an M4-sized rifle, so it was inevitable that the rifle was going to grow."
The rifle is about as ambi as it comes. This includes a selector lever, bolt catch/bolt release, and a magazine catch/release on both the left and right-hand sides of the lower receiver.
It has two charging handles – a rearward handle that is familiar to any AR/M4 user, and a side-mounted non-reciprocating charging handle on the left of the upper, akin to that seen on a G3/HK91 or SCAR NRCH. It folds to a low profile.
The MCX Spear has a user-swappable barrel and barrel extension held inside two T27 Torx screws in a self-contained clamp. Just loosen it up and swap it out for a shorter barrel or a different caliber. It doesn't get much more modular than that. Sig has a commercial version of the gun in .277 Fury and 6.5 CM with .308 Win models coming soon. Sig also plans a Sig MCX Spear Rattler with an 8-inch gas trap barrel that, with hybrid ammo, will still provide carbine-like velocity.
For those quiet moments, the MCX Spear has a two-position gas valve – "normal" and "adverse," each with its own suppressed and unsuppressed settings – that allows the user to tweak the gas system for different ammo types and field conditions. Keep in mind that the Army may have to use the rifle anywhere from the polar regions to the jungle and desert.
The XM250 has an extendable buttstock. Sig also offers the gun with a side-folding stock, so that already exists should the Army look for a more compact LMG down the road.
The charging handle is on the left side of the XM250's receiver while the feed tray opens from the left as well, rather than the top as on some other machine guns. Sig said this is so the feed tray doesn't interfere with in-line optics mounted on the gun's top Pic rail.
The machine gun has a quick-change barrel with a self-contained clamp that can be changed in seconds. This feature also allows the gun to swap between its standard 6.8 caliber to, for instance, a 7.62 NATO caliber, in minutes.
Firing from an open bolt, the XM250 has a three-position safety: safe, full auto, and semi. Unlike other designs, it can be loaded with the bolt forward and charged with the selector on safe.
Like the MCX/XM5, the X250 has a two-position ("normal" and "adverse") gas valve, each with suppressed and unsuppressed settings.
The hybrid bi-metallic case on the 6.8x51mm cartridge developed for the Army by Sig uses a steel base/head and a brass case to allow the pressure to go from the traditional ~68,000 psi of an all-brass case to the region of 120K psi without any failure while still using conventional primers and powder. This translates to a 350 fps boost in velocity. Alternatively, this also allows for 16-inch-barrel-level velocities from an 8-inch barrel or a 24-inch-barrel-level velo from a 14-inch barrel.
Still curious and want more? Check out St. John's full 18-minute talk and demo, below, filmed front and center at Freedom Days, an event that is likely coming closer to your area in future months.