Footage dating back as early as 2011, shows a United States soldier in Afghanistan firing the German MG3 from the standing, shoulder position.
Now I'm not sure how many of you were/are machine gunners during your military career, but during my service, I tried this with the United States equivalent (240 L and/or 240 B) and let me tell you something, it's not easy. For starters, the MG3 weighs 25.35 pounds alone (240 L - 21.8 lbs, 240 B 27.3 lbs). On top of that, you add at least 5 to 10 pounds of ammo to the mix. Regardless of who you are, that's a heavy load to be holding in the ready position, while also considering the shooters accuracy and effectiveness.
Without (Insert Ackchyually Gif) critically analyzing the footage, 99% percent of these videos of people shoulder firing 7.62x51 is for the memes and big PP ego.
For all you beef cake, husky guys out there saying, 'Nah bro, I'm a gamer when it comes to shoulder firing 7.62x51 machine guns', go to sleep. Your shots are inaccurate and you suck. :)