Browning demonstrated the M-1917 belt fed machine gun to the Army. Linking belt after belt, he fed ammunition to it, and it fired, and fired. He topped of the water jacket in between attaching belts. Eventually after 45 minutes of continuous fire, he had exhausted all the ammunition. No stoppages. Nicht, Zero, Nada.
He then pulled out a handkerchief and tied a blindfold over his eyes. He disassembled the gun blindfolded, putting each part on a table in front of the assembled officers, down to the last part. He then reassembed it blind folded and performed a function check. It is important for soldiers to be able to perform maintenance on machine guns in the dark, without lights.
He did it again a few months later, because some of the officers thought it might be a trick.
That amazing “M-1917 blindfolded field stripping and reassembly” trick was also important for Marines, especially GySgt. John Basilone, on Guadalcanal, October 24 - 24, 1942. Seventh Marines, First Division. His Congressional Medal of Honor citation actually read “. . . contributed in large measure to the virtual annihilation of a Japanese regiment.” Those guys ran out of water, though, and so they refilled the water jackets of their guns with urine.
There is a funny story about Maxim and his gun in Russia. Maxim arrived in Russia with his gun to demonstrate to to a bunch of Czarist officers. While he was awaiting the demonstration date and his gun and belted ammunition to arrive at the site, he was shadowed by the Czar's secret police, the Okhrana.
When the demonstration day came, Maxim explained the operation of his gun to the Czar's officers who had no idea what an automatic machine gun was. These officers’ only exposure had been to the manually cranked Gatling (called Gorloff by the Russians). When Maxim explained about the cocking handle and how it cycled with the gun, one officer said he'd like to see a soldier move the handle at 660 rounds per minute!
Maxim inserted a belt, cocked the gun twice to index the belt and chamber a round. He then pushed the trigger bar and fired the whole belt of 300 rounds without touching the cocking handle — that continued flipping back and forth as the gun fired.
The Russian officers were absolutely dumbfounded by what they had witnessed. The recommendation was the Maxim be adopted in numbers for the Russian Army. The Maxim soldiered with the Russian Army from 1910 and into the 1950s before it was replaced by lighter and newer designs.