How in the hell are boxes of bullets lying around in a medieval monastery?
We don't exactly know the entire history of the estate or the area around it. For all we know, it was temporarily taken over by the British military during WWI, when various panics regarding a German invasion or an Irish uprising (like what happened in Dublin in 1916 and what eventually broke out after the war) meant it was temporarily garrisoned until it was evacuated following independence, leaving several tons of equipment behind for anybody to use. And we ALSO don't know exactly what the Covanent clan has been doing in the meantime, but since it is apparently possible to travel back in time, it might even be that they did so and left the bullets.
