Review: SIG Sauer Tango6T And Alpha4 Mount

SIG Sauer has gone from simply being a “gun maker” to a one-stop shop for all firearms needs, from cartridges to suppressors. Our tests of the MCX-SPEAR LT illustrate this, as SIG was able to provide us a package of a rifle, ammunition and scope that the company manufactures.

For testing purposes, our sample rifle used SIG’s Tango6T 1-6X 24 mm Direct View Optic (DVO) mounted to the rifle with its Alpha4 cantilever mount. The Tango6T is a version of the scope that has been adopted by the U.S. Army for use on the M110A1 Squad Designated Marksman Rifles (SDMR) and SOCOM. If you’ve seen pictures of the XM7 and XM250 being tested in the NGSW trials, this is the optic that they were using.

SIG's Tango6T 1-6X 24 mm DVO scope comes with its Alpha4 cantilever mount and lens covers, as supplied to the U.S. Army. Photo courtesy of SIG Sauer.

The Tango6T uses an illuminated bullet drop compensator reticle SIG calls the Hellfire DWLR-556 FFP. The reticle, which is both fiber optic and etched into the scope’s glass, features a black post surround by an illuminated “donut” with subtension markings for ranges out to 800 meters and wind/moving target hold offs.

Since the scope is first focal plane, on the lowest power, the complex reticle shrinks to almost a single aiming point for quick acquisition. As the scope’s power is increased, its ballistic subtensions are visible and accurate at any power. The illumination has nine daylight and two night-vision-compatible settings with a locking ring to secure the desired brightness. The scope is powered by one CR2032 battery that is rated with a 100-hour life at the mid-brightness settings.

The SIG Tango6T 1-6X 24 mm DVO rifle scope uses an illuminated ballistic compensating Hellfire DWLR-556 FFP reticle. The reticle has range and windage subtensions. Photo courtesy of SIG Sauer.

Windage and elevations knobs have caps to cover them when not in use, with each click providing 0.2 MRAD of adjustment. The dials can be zeroed once a scope has been sighted in.

A review of the Tango6T could use many of the same criteria we have used to evaluate a peak rifle. The scope is rugged and proven. Its HDX lenses are high definition and high transmittance with SIG’s LensArmor protective coating and SpectraCoat anti-reflective coating. It is IPX8 waterproof rated (1.5 meters for 30 minutes). The Tango6T DVO comes equipped with scope caps that are secured open with magnets when flipped out of the way.

The SIG Tango6T 1-6X 24 mm DVO scope uses SIG's LensArmor anti-scratch coating and SpectraCoat anti-reflection coating and comes equipped with lens covers that are held in place with magnets when opened. Photo courtesy of SIG Sauer.

The Tango6T is relatively lightweight and compact for its power. The scope and mount weigh in at 27.9 ozs., putting the MCX-SPEAR LT with scope mounted at just over 9 lbs. The scope’s overall length is 11.56”.

The scope has many user-friendly features, including subtle mounting aids. These include the torque specs and tightening order for the ring bolts marked on the mount and laser-etched marks on the scope body to help ensure level alignment. The scope illumination and adjustment dials, eyepiece focus and magnification (it comes supplied with a throw lever to speed up magnification changes) are easy to use.

To aid in properly mounting the scope, the SIG Alpha4 cantilever scope mount has its ring bolts marked with torque specs and tightening sequence. Photo courtesy of SIG Sauer.

Modern low-power variable optic scopes share the features of the “peak rifles” they are mounted on, being compact, rugged and versatile, allowing the use of the 5.56 mm cartridge from close quarters to its maximum effective range. Like the rifles, this performance comes at a price. The MSRP for the Tango6T and mount is just under $3,000.