Black Phase Tactical LLC upper receivers:
US manufactured from 7075-T6 Forged aluminum.
Square forge mark is from Brass Aluminum Forging Enterprises.
Machined to Mil spec TDP dimensions.
Mil spec hard coat type III anodized.
Laser T marked on the top rail.
M4 feed ramps.
Available with standard or teardrop forward assist.
Includes dust cover.
About the term "single track"...
The best way to determine if wolves are present is to find their tracks. Wolf tracks are fairly easy to pick out, as they can be more than twice as big as a coyote's. They can sometimes be confused with the tracks of large dogs, but the key is in how they walk. Whether it's on a packed trail, or through deep snow, a wolf wastes very little energy while traveling. Their tracks are nearly always in a straight line, with the left and right paws only slightly offset (usually 6 inches or less). Compared to wolves, dogs walk like they're drunk. Their tracks are distinctly scattered, and often appear more "wandering.". Even on hard trails, dogs tend to drag their toes when they walk, whereas wolves generally leave a cleaner stride. In deep snow, distinct tracks are rarely visible. Look for a narrow trail with in-line footprints. When a pack runs through deep snow, they usually step in the same tracks as the wolf in front of them, which leaves even more pronounced prints. Also, you can usually see where their bodies have pushed a trail through the snow. The way they travel often makes it tough to determine how many are in a pack.