The Federov was issued to only one company, for testing, just before WWI broke out. It was used in combat, but never got into even batch production until 1920, then was never mass produced because better rifles were coming along. It was chambered for the 6.5x50.5 Japanese round.
The Mauser never got into even limited production.
The Mondragon was the only rifle of the three that had any substantial issue, but it reportedly was not very reliable.
There was not a lot of use of the BAR in WWI. It was demonstrated in France in June 1918, but significant numbers were not available until September. Even then, few were issued as Pershing wanted to wait until there were enough to equip the whole American army. (Like most other commanders, he expected the war to last into 1919.)
There was some combat use starting in late September, but the armistice was on 11 November, so the BAR's role in France lasted only a month and a half and was very limited.
Needless to say, those who would have chosen an M1 rifle, an M14, or a 7.62mm Minigun would have had a long wait.
Jim