Mystery Cylindrical Objects

Do you recognize these? I sure don't, and I have no information about them other than the fact that they were found together with some dummy sources. My best guess is that these aren't sources at all, but you never know. They are 7/8" long and 3/8" in diameter, their ends are convex, there are no welds, no markings of any kind, and there does not appear to be an internal cavity. An XRF analysis reveals that it is a zinc-iron alloy. If it was intended to be activated, an exposure to neutrons would primarily produce Zn-65. One unusual feature is that each one has three triangular grooves cut into one end. Presumably, this facilitates manipulation with some sort of handling tool. Perhaps they were intended to help wedge these things inside a tight fitting container. Tom Dowling has suggested that these are likely retention pins used to help line up equipment/machinery components.