The guns used in the film were not even actual MP5s. They were actually similar HK94 semi-automatic carbine rifles whose barrels were chopped down and converted to full auto to resemble MP5A3s.
Colonel Stuart and Major Grant's men all use MP5s with "jungle style" magazines, (two magazines joined together with tape). Two versions of these guns are seen: magazines with red tape or blue tape. There is a massive firefight between Major Grant and Colonel Stuart's men, during which John McClane picks up a discarded MP5 with blue tape. McClane checks the load, and discovers that the gun was carrying blanks, and deduces that the ones carrying live ammunition must be the ones with red tape. McClane fired the gun at Carmine Lorenzo to prove that the firefight was staged and that Stuart and Grant were in cahoots, nearly getting shot in the process. McClane proves his point, and Lorenzo gets his men on it.
In this film, there were three variants of MP5s used, including the MP5A3, the MP5A5, and the MP5K, a scaled down version with a fore-grip.
During the cargo ship sequence, John McClane takes an MP5K off a dead terrorist and gives it to Zeus Carver before sending him off to find Simon Gruber. When Zeus does, he corners Simon and threatens to kill him if he doesn't give out the code to disarm a bomb. Simon refuses and Zeus pulls the trigger, only to find that the safety catch is on. Simon casually takes the gun from him, revealing that the safety was on.
Unlike the previous films, the terrorists in this one do not use the MP5 as a main weapon, instead opting for more futuristic looking weapons. However, they do make a brief appearance. The FBI is seen holding MP5A2s (The MP5A3 with a fixed rubber butt-stock), and MP5A3s (Same gun but with collapsing stock).
Irina uses an MP5K-PDW, which is an MP5K with a threaded barrel. She attaches a silencer to her MP5 and also has a scope on it.
- The MP5A3 and MP5A5 both feature a gun strap, factory sights, a detachable 30-round curved box magazine, a selector switch and a folding stock.
- The MP5Ks do not have folding stocks and feature a fore-grip under the shortened barrel, and the MP5A2 is identical to the MP5A3, only with a fixed butt-stock.
- Although the gun was European and was only used to contrast the weapons between the terrorists and the LAPD, law enforcement around the world soon began using it.
- Besides the Beretta 92 pistol, the H&K MP5 is the only weapon seen in all five Die Hard films.
- Each film features a different MP5 variant, meaning that there is no one type of the MP5 that is seen twice. Die Hard featured the HK94 carbine, Die Hard 2: Die Harder featured the MP5K, MP5A3, and MP5A5, Die Hard with a Vengeance featured the MP5K, Live Free or Die Hard featured the MP5A2, and A Good Day to Die Hard featured a MP5-PDW with silencer.