Feeder mechanism for feeding mechanical fasteners, such as rivets, screws, bolts and similar, comprising: a transport means for transporting mechanical fasteners, preferably by pressurized air; and a stopping and aligning unit for mechanical fasteners arranged downstream of the transport means, comprising: a stopping plate which is configured to have at least a first position and second position, wherein in the first position a fastener supplied by the transport means is decelerated, and wherein in the second position the supplied fastener passes the stopping plate; at least one aligning jaw (123a, 123b, 123c) being arranged downstream of the stopping plate and being configured to have at least a first position and a second position, wherein in the first position the aligning jaw (123a, 123b, 123c) aligns the supplied fastener, such that it may be picked by a gripping device, and wherein in the second position the aligning jaw (123a, 123b, 123c) releases the supplied fastener, characterized in that, the aligning jaw (123a, 123b, 123c) is configured to have a third position, wherein in the third position an aperture formed by the aligning jaw has an inner diameter which is larger than the outer diameter of a shaft of a supplied fastener, but smaller than the outer diameter of a head of a supplied fastener, wherein the third position is preferably adjustable. a transport means for transporting mechanical fasteners, preferably by pressurized air; and a stopping and aligning unit for mechanical fasteners arranged downstream of the transport means, comprising: a stopping plate which is configured to have at least a first position and second position, wherein in the first position a fastener supplied by the transport means is decelerated, and wherein in the second position the supplied fastener passes the stopping plate; at least one aligning jaw (123a, 123b, 123c) being arranged downstream of the stopping plate and being configured to have at least a first position and a second position, wherein in the first position the aligning jaw (123a, 123b, 123c) aligns the supplied fastener, such that it may be picked by a gripping device, and wherein in the second position the aligning jaw (123a, 123b, 123c) releases the supplied fastener, a stopping plate which is configured to have at least a first position and second position, wherein in the first position a fastener supplied by the transport means is decelerated, and wherein in the second position the supplied fastener passes the stopping plate; in the first position a fastener supplied by the transport means is decelerated, and wherein in the second position the supplied fastener passes the stopping plate; at least one aligning jaw (123a, 123b, 123c) being arranged downstream of the stopping plate and being configured to have at least a first position and a second position, wherein in the first position the aligning jaw (123a, 123b, 123c) aligns the supplied fastener, such that it may be picked by a gripping device, and wherein in the second position the aligning jaw (123a, 123b, 123c) releases the supplied fastener, in the first position the aligning jaw (123a, 123b, 123c) aligns the supplied fastener, such that it may be picked by a gripping device, and wherein in the second position the aligning jaw (123a, 123b, 123c) releases the supplied fastener, characterized in that, the aligning jaw (123a, 123b, 123c) is configured to have a third position, wherein in the third position an aperture formed by the aligning jaw has an inner diameter which is larger than the outer diameter of a shaft of a supplied fastener, but smaller than the outer diameter of a head of a supplied fastener, wherein the third position is preferably adjustable.