The screws attaching the bows to the side rails (Fig. 321, Item 6) calls out as 5305-00-059-3659  with a general fastener number of MS51958-63 is essentially a 10-32 x 1/2″ pan head screw. Although we feel a standard 10-32 screw would be sufficient, we were able to source a number of the actual fasteners designated MS51958-63 at around the base price of the fastener from major vendors.
Although it is highly likely that a standard 10-32 screw would suffice in this application, we feel that use of the correct military fastener may give a slight performance advantage in both strength and corrosion resistance.
Of note, however, the fasteners we acquired indicate they are stainless, which is generally of a strength equivalent to a Grade 5 bolt. (of course, this depends on the type of stainless). We believe the vendor has mistaken plated fasteners as stainless. The packaging of the fasteners state they are MS51958-63. We have not reviewed the specifications of this fastener, but are of the opinion that even if stainless, they should suffice for holding the bows to the side rails.