Fiber optic connector sub-assemblies having a front-loading locking ferrule holder and related fiber optic components, devices and methods

A fiber optic connector inner housing employing a front-loading retention feature for receiving and retaining a ferrule holder, and related fiber optic connectors, cables, and methods are disclosed. In one example, the inner housing has an opening extending therethrough and at least one bayonet locking mechanism that includes an insertion slot, a rotation slot, and a retention slot disposed in an interior surface of the opening. A ferrule holder having a key portion is inserted into the opening such that the key portion is received by the insertion slot. The ferrule holder is next rotated in the rotation slot and released such that a bias member within the inner housing moves the key portion of the ferrule holder into the retention slot, thereby retaining the ferrule holder in the inner housing and preventing accidental removal of the ferrule holder from the inner housing.