Put a 15 round magazine on a Remington Model 8.
That's doable in 1901, when it was first patented.
Now it was double the price of a bolt action, and .30 Remington was no more than Win .30-30 without the rim, so less powerful than the 30-06, which is what we want.
Now as built, the Model 8 is terrible for military service, while being an take-down model, with Barrel and recoil unit is easily removed for cleaning, not so for anything in the Receiver, for removing the trigger group or bolt.
So our M1901 would soon have be revised, to M1901A1 with a removable top cover, like an AK, that was 'inspired' by this Remington in its trigger group and safety setup.
John Browning was a smart guy, if Army said, 'make it easier to service' BOOM, next model would be easier.
Now this was a single stack magazine, not easily removed, as it was to be fed by using chargers, not removing the mag.
So say your M1901A2 get that feature, detachable magazine, while still able to use chargers.
So the US Cavalry has this before WWI, where they may be desire for an automatic weapon, that's the M1901A4 or so, select fire by 1918