pretty clear that this was no shield, it was a battering ram.
In seconds they make up the ground between their positon and the beast. Steve tries to steady himself with one hand and aim over the top of the plate as it gets in closer, hoping for a lucky shot or two, but when it makes contact the impact is heavier than he anticipated and the entire vehicle rocks backwards, throwing him from the roof and into the mud to the rear.
As he lands the battering ram makes another heave and rams the beast again, pushing it towards where he lies and he scrambles to his feet to avoid it just as the remaining drones charge around the front of the vehicle to attack him.
The flares are fading however and in the dim light they hesitate for