When you start out, you are carrying it and all its ammo and bi(tri)pod, then you change firing modes and it makes you put it down and set it up on a bipod so you can fire it. Change modes again and you take it down and carry it again. Maybe not too realistic because it is a crew serviced weapon, maybe the less reliable M60e3 would be more realistic. Some of us like to just sit there and shoot everything! .. i mean... provide cover fire
http://www.fas.org/man/dod-101/sys/land/m60e3.htm
http://www.fas.org/man/dod-101/sys/land/m60e3.htm