From the pic's it is hard to tell which grenade fuzes these are. They can be from smoke or frag. If you remove the fuze you can tell what type fuze it was. I've never seen a grenade fuze melt from the heat, and most fuzes actually survive the detonation form a HE grenade. One note if you look at the top of the fuzes you can see the percussion primer has been hit by the striker at least once. Dud fuze?? Which makes me ask did someone put this together? In my time on VN and research on NVA/VC grenades I have found one similar, but they used a fully functioning fuze. One can take a fired grenade fuze punch out the functioned primer, press in a large rifle or shotgun primer then secure in place a piece of time fuze to the out put end of the primer. This was not seen in VN as the NVA/VC in the field did not have fresh primers to use. But has been seen here in the US, especially with practice grenades that the bad guys tried to load with black powder or other materials.