The Model 1917 / M1917 Browning Machine Gun was a recoil powered automatic firearm. It was granted US Patent 678937 on July 23rd, 1901. This patent was applied for on June 19th, 1900. So why was this Machine Gun given the name Model 1917 when the model number usually mirrors the patent year plus or minus one year? The name is actually based on the fact that this firearm was not adopted for use until 1917. The design sat around for years until the US Military found itself in need of some high power high output firearms. Along came the Model 1917 after spending some years in hibernation.
A key feature of the M1917 is that it was a water cooled machine gun. This was a factor in the weight and thus restricted some applications. The 1917 eventually morphed into multiple other versions / variations including the M1919.
Another key feature that should be mentioned is that this patent has a right side ejection of spent rounds where the M1917 would adjust it to bottom ejection.