During the 2nd Battle of Buenos Aires, the 95th Rifles were heavily engaged in street-fighting, during which Plunket killed around 20 Spanish troops while sniping from a rooftop with others from his unit.

Plunket ran forward from the British line about 90 metres (100 yd), lay down in a supine position in the snow, and shot the French Général de Brigade Auguste-Marie-François Colbert with his Baker rifle.

Plunket only just made it back to his lines before being charged down by a dozen cavalry troopers, but the deaths of the two officers were sufficient to throw the pending French attack into disarray.

Their marksmanship was far better than the ordinary British soldiers, who were armed with a Brown Bess musket and only trained to shoot into a body of men at 50 metres (55 yd) with volley fire.

A historian familiar with the area asserts it was no less than 200 yards, a remarkable feat given the Baker rifle's limitations and the moving target.