December 31, 2020
The War on Terror taught our military the importance of precision rifle fire. Sure, “fire superiority” is a valid concept because shooting a lot in one direction will definitely encourage the enemy to keep their head down, while friendly elements maneuver to the target. However, nothing brings a fight to a screeching halt like a well-placed shot. One of those in the right place, and none of your friends have to run anywhere. Problem solved; problem staying solved.
The challenge was, until September 11, 2001, our military had no mechanism to ensure precision riflemen were present at the squad level where they’re needed most. An infantry squad consists of about nine soldiers and is a basic maneuver element. It does the heavy lifting in any war by patrolling through enemy territory. When American soldiers make contact with the enemy, it is most likely at the squad level. It makes sense that there should be at least one squad member trained and equipped to deliver precision fire in support of the squad.
This concept gained rapid acceptance when the war started, and we’re just now getting a dedicated rifle and optic combination into our soldier’s hands. The rifle is the new M110A1 SDMR made by HK. The scope is the Tango6T 1-6x24mm made by SIG Sauer.
It’s important to clarify the differences between a sniper and a designated marksman. A sniper attends a 6- to 8-week course that covers everything from shooting to fieldcraft to mission planning. The squad designated marksman (SDM) program is solely focused on advancing the shooting skills of a unit’s top expert-qualified shooters using irons and optics. SDM training typically lasts 2 weeks. The end-state is to consistently hit man-sized targets out to about 600 meters, or 660 yards. Predictable rifle fire for distances out to 600 meters is improved with the employment of quality optics.
The U.S. Army wanted a first focal plane (FFP) reticle for this scope, so that’s what SIG Sauer gave to them. SIG Sauer initially developed a ballistic drop compensating (BDC) reticle for the M80A1 round at the Army’s request, which was called the “7.62 Extended Range” reticle. Later, the Army requested (and now issues) a BDC reticle developed for M118LR, a 175-grain Match load, which is also issued to snipers. The reticle developed for M118LR ammunition is the “Dual Wind holds Long Range 6X magnification,” or “DWLR6.”
Nobody knows why the Army started with one ammunition type and then changed mid-solicitation. My guess is the M80A1 ammunition couldn’t meet the accuracy requirement for the SDM role. The M80A1 bullet is a 130-grain lead-free round that is made of a copper jacket, a copper plug that sits in the bottom of the jacket, and a pointed steel penetrator that forms the bullet’s nose. That combination is a concentricity nightmare, and I’d be shocked if the M80A1 would hold a 4-inch group at 100 yards. So, the Army asked SIG Sauer to design a second reticle around the M118LR, which is loaded with a 175-grain MatchKing. It’s good, solid ammunition.
The reticle SIG Sauer designed for the Army has a floating center dot with an inverted horseshoe around it. These are the only two components of the reticle that illuminate, but they function as well as a red dot when the scope is set at low power such as 1X or 2X. With higher magnification, the center dot allows for precise shot placement.
Descending from the center dot is a vertical stadia line that’s marked for 50-meter increments out to 1,000 meters. Each 100-meter mark is a horizontal hash, and the 50-meter designations are dots. It’s an effective way to get fast holdovers for a moderately trained rifleman.
At each 100-meter hash there are two flanking dots at increasing horizontal intervals that give the reticle its “Christmas tree” shape. Those dots are holdoffs for either wind or moving targets.
While I’m not normally a fan of BDC reticles, the Army put one in this scope because 1 to 3 weeks of training isn’t enough time to teach a soldier how to use a ballistic calculator, considering all the other tasks that need to be covered. A BDC reticle simplifies and speeds up the aiming process at the expense of precision. BDC reticles are very precise when conditions match the “ideal” around which the reticle is designed: ammunition, temperature, elevation, etc. Once one of those elements change significantly, the BDC reticle only becomes a generalization. Fortunately, SIG Sauer also publishes the data for each subtension mark on their BDC reticle in mils. This allows the reticle to work for cartridges other than M118LR and M80A1, although not quite as seamlessly.
Besides its function and features, SIG Sauer’s Tango6T scope won the contract because it is an extremely durable and weather-resistant optic. Ensuring robust construction was a serious consideration during the design process. I spoke to Andy York, president of SIG Sauer’s Electro-Optics, and he said, “We wanted to build an extremely durable product here in the U.S. We redesigned the waterproofing around the turrets and made a lot of improvements to overall optic durability. All of those changes are now offered on all versions of the Tango6 1-6X.”
In pursuit of building this scope for the U.S. military, SIG Sauer built a 3,000-square-foot clean room where components sourced from around the world are assembled into scopes. All assembly and testing is completed at their Oregon facility.
Each Tango6T is tested to ensure the illumination system works correctly. The scope has a locking illumination turret and illumination settings that work with both clip-on night vision devices that sit in front of the optic, as well as operator-worn night vision goggles (NVG). SIG Sauer also checks each scope for light leakage when viewed from the rifle’s business end. Some illumination systems are visible from downrange when observed through night vision devices. The Tango6T doesn’t exhibit this giveaway.
Each scope goes through impact testing and a recoil simulation machine, and they also get submerged in a water tank to verify waterproofing. Perhaps my favorite durability-enhancing step is the use of epoxy in all the lens housing groups. The number one cause of point of impact shifts in any optic is lens movement. Smack a scope from the side and there’s a good chance one of the lenses inside the tube moved. Even .001-inch of lens movement will result in a point-of-impact shift. SIG Sauer takes the additional step of bedding to hold all lens housing groups in place. Once each group is threaded in place, epoxy ensures it never moves again.
It’s taken a while for the U.S. Army to get here, but squad designated marksmen now have a simple and robust optic that will help them successfully complete their mission. SIG Sauer is also offering this scope commercially, one of the few times it’s been possible to purchase the exact same optic our military’s marksmen use.
Enjoy articles like this?
Subscribe to the magazine.
Get access to everything Guns & Ammo has to offer.
Subscribe to the Magazine