Identifying firing distance from a bullet wound depends on which muzzle products reach the skin. The bullet itself always creates an abrasion collar (AC) and may wipe a grease/dirt collar (GC); these are range-independent. Range is read instead from flame (burns), soot (blackening), and powder grains (tattooing).
In this wound the AC and GC are present, but tattooing, soot, and burning are all absent. Powder grains travel only a limited distance - tattooing extends to about $60\,cm$ and soot to about $30\,cm$. When the muzzle is farther than the powder can travel, only the bullet-related marks remain.
Hence the absence of every accessory powder/flame effect places the muzzle beyond powder range. This is the classic appearance of a far or distant shot.
A contact wound would show a muzzle imprint with internal soot; a close shot would show heavy blackening and singeing; an intermediate shot would show stippling. The clean wound with only AC + GC excludes all of these.
\[\boxed{\text{AC + GC, no tattooing/soot/burn} \Rightarrow \text{Distant range}}\]