Abstract: A large capacity agricultural irrigation sprinkler head of the rotary step by step impulse type operating in a part-circle mode with a step by step reversing movement. The sprinkler head embodies an improved sprinkler body including an elongated barrel leading to the outlet having a longitudinal axis intersecting (1) at an included angle greater than 90.degree. with the rotational axis of the sprinkler body and (2) at an angle of 90.degree. with the pivotal axis of the impulse arm assembly at a position spaced outwardly in a downstream direction from the intersection thereof with the sprinkler body rotational axis. The impulse arm is mounted by a yoke pivotally mounted on the barrel about an axis constituting the pivotal axis of the impuse arm for movement between first and second operating positions corresponding to the first and second operating positions of the impulse arm and pivotally connecting with the impulse arm about an axis constituting the oscillating axis of the impulse arm.