In my Vietnam EOD tours I never saw a Viet Cong grenade with screw-on metal cap. The VC did not have manufacturing facilities for the most part that were capable of making the caps. They simply machined/carved wooden plugs that were force fit into the end of the wooden handle. Most of the time the pull cord in the handle was just a piece of twisted cord with no attachment on the end to grab like the one shown here. The only screw-on capped grenades I encountered in the Danang operational area and the Pleiku operational area were clearly Chinese. The VC, however, did often use tin cans for their grenade bodies. I have a Ballentine beer can in the collection. They normally used beer or soft drink cans because that is what the GI's left laying around the countryside. I do not recall seeing any cans with ridges like these, but I am not sure my level of detail in my memory banks would recall that at this point.