A fiber optic connector, comprising: a ferrule having a mating end and an insertion end; a ferrule holder having a first end portion in which the ferrule is received and a second end portion opposite the first end portion, the first end portion defining a first bore having a first bore width (W 1) for receiving the ferrule, the second end portion defining a second bore having a second bore width (W 2), the ferrule holder further including a third bore between the first and second bores (92, 96), the third bore having a third bore width (W 3) smaller than the second bore width (W 2); wherein: the first end portion of the ferrule holder further defines a bore surface and at least one groove formed in the bore surface; the at least one groove extends from where the insertion end of the ferrule is located within the first bore to a front face of the ferrule holder; the at least one groove also extends in circumferential direction so that ridges are formed around the first bore; and the at least one groove comprises an internal thread such that the ridges formed around the first bore are helical; characterized in that the at least one groove has a depth (d) that is from about 2% to about 3.5% of the diameter of the ferrule and the internal thread has a pitch (p) that is from about 10% to about 12% of the diameter of the ferrule so that the ridges contact the ferrule and are deflected by the ferrule in a direction toward the insertion end of the ferrule. a ferrule having a mating end and an insertion end; a ferrule holder having a first end portion in which the ferrule is received and a second end portion opposite the first end portion, the first end portion defining a first bore having a first bore width (W 1) for receiving the ferrule, the second end portion defining a second bore having a second bore width (W 2), the ferrule holder further including a third bore between the first and second bores (92, 96), the third bore having a third bore width (W 3) smaller than the second bore width (W 2); wherein: the first end portion of the ferrule holder further defines a bore surface and at least one groove formed in the bore surface; the at least one groove extends from where the insertion end of the ferrule is located within the first bore to a front face of the ferrule holder; the at least one groove also extends in circumferential direction so that ridges are formed around the first bore; and the at least one groove comprises an internal thread such that the ridges formed around the first bore are helical; the first end portion of the ferrule holder further defines a bore surface and at least one groove formed in the bore surface; the at least one groove extends from where the insertion end of the ferrule is located within the first bore to a front face of the ferrule holder; the at least one groove also extends in circumferential direction so that ridges are formed around the first bore; and the at least one groove comprises an internal thread such that the ridges formed around the first bore are helical; characterized in that the at least one groove has a depth (d) that is from about 2% to about 3.5% of the diameter of the ferrule and the internal thread has a pitch (p) that is from about 10% to about 12% of the diameter of the ferrule so that the ridges contact the ferrule and are deflected by the ferrule in a direction toward the insertion end of the ferrule.