Nonactuatable

upon the hammer arriving at full cock the draw rod becomes disengaged with the grip housing and nonactuatable thereby,

Source: wiktionary

(g) control means for said switch means for rendering said switch means actuateable or nonactuatable.

Source: wiktionary

Therefore, W is defined as the nonactuatable portion of the DEA (i.e. the amount of DEA material that, although available for actuation, yet, cannot be actuated).

Source: wiktionary