A cap for a field-installable optical connector having a front and rear orientation, a housing, an axially-actuated clamping mechanism in the housing, and a ferrule assembly forward of the clamping mechanism and forwardly biased in the housing, the ferrule assembly comprising a holder and a ferrule extending from the holder, the cap comprising a front end defining a cavity for receiving the ferrule and having an outer surface defining at least part of a front-end geometry, a back end defining an opening through which the ferrule is received and a perimeter around the opening, the perimeter configured to contact the holder when the cap is pushed rearward in the housing, the front and back ends being unitary such that any rearward force on the front end is transferred to the back end and through the perimeter to the holder and a retention portion for contacting the housing to secure the cap to the housing.