There's a tendency to distribute man-portable weapons into the small manoeuvre units and to keep the crew-served weapons pooled at a higher level (with tripod machine guns being the water shed that moved into platoons after WW1).

A battalion fire support unit would thus use mortars or crew-served anti-tank weapons rather than a 7 kg MGL.

An exception are snipers which should be in a Bn Sniper Plt, but their employment is very distinct from the normal infantry employment (thus sharpshooters within the infantry).