This study concerns the development and trials of assault rifles/battle rifles in Sweden during 1959-1964, which led to the adoption of Automatkarbin 4(Automatic Carbine 4) chambered in 7.62x51. The purpose of the study was to gauge the trials and the factors influencing the choice of weapons platform andcaliber through the theory Social Shaping of Technology. The research questions were: “Why and how did Sweden pick Automatkarbin 4?” and “Why and how did Sweden pick the 7.62x51 caliber?”. The method used is qualitative text analysis.The conclusions are that Sweden picked Automatkarbin 4 and 7.62x51 because they were the optimal weapons platform and caliber respectively that conformed to the social constructs of what was categorized as desirable traits, motivated by a relatively short trials period of only 5 years and the need to select an internationally widespread caliber.