The marines' smart guns weighed , and were constructed from German MG 42 anti-aircraft machine guns attached to a steadicam and augmented with motorcycle parts. Since getting in and out of the smart-gun rig was difficult, the actors kept them on when not filming. The pulse rifle was made from a Thompson submachine gun and a Franchi SPAS-12 pump-action shotgun in a futuristic shell. Weaver was opposed to weapons in general, but Cameron explained weapons were secondary to the core narrative of Ripley bonding with (and protecting) Newt. Weaver found using the weapons strange and difficult, due to their weight and her concern about pulling the wrong trigger.