I'm still not understanding what I am looking at.

The plasticiser is the bit that converts granular plastic to melt. This has to connect to the mould, inject the melt, hold the pressure until something freezes, gates, sprue, whatever, disconnect from the mould and melt more granules.

Generally there are 3 ways in to a mould. On the mould parting line, through a sprue bushing, through heated runners where the melt never sets.

I thought that sprue bushing was usually a flat on flat seal with maybe a puff of cold air if stringing got too bad.

I thought I saw something like a countersunk screw head shaped cavity in your picture which would be fine and dandy if it was on the mould parting line because you wouldn't have to worry about getting it all out before the next shot.