Complex sentence: In the early 1980s the manufacturing of the HK G3 and HK 21, under license from Heckler & Koch, by INDEP allowed for the import of German weapon manufacturing machinery and German technical know-how, which stimulated development of new firearms design in Portugal.
Split into simpler sentences: In the early 1980s, INDEP manufactured the HK G3 and HK 21 in Portugal under license from Heckler & Koch. This allowed for the importation of German weapons manufacturing machinery and technical know-how, which stimulated development of new firearms designs in Portugal.