What is "scmitr"

SCMITR was part of an experimental military shotgun ammunition created in the 1970s by AAI Corporation. It was a variation on flechette ammunition, but instead of containing a bundle of tiny needle-like steel darts, the cartridge contained a stack of razor-edged stamped sheet-metal arrow shapes designed to fly aerodynamically. It was considered to be very promising (in terms of lethality and effective range) but prohibitively expensive to manufacture, so it has never been mass-produced.