For a big, heavy support firearm, the Browning has a relatively small bite to go with its bark. The biggest problem with the Browning is the fact that it uses 30.06 rounds, which are a mid-game ammunition not meant for late-game guns, especially when you've been using all of the limited amounts of 30.06 in the M1 Garand. The low amount of damage coupled with the low accuracy and lack of AP capabilities also cripple its use against the robots. All in all, you'll be much better off with a lighter FN FAL, or a more powerful M249 SAW.
The M1918 Browning automatic rifle, more commonly known as a BAR, was developed by John Browning in 1917 for the U.S. Expeditionary Corps. Mass production of the BAR came to a halt when superior rifles with less recoil were produced. The BAR was mass produced from 1917 to 1950, with a supposed 100,000 made during this period of time.