Why is it that the AY69 has more accurate hipfire than the Grendel? I thought a machine pistol should be very inaccurate compared to an assault rifle designed for accuracy and range...

Why is it that the AY69 has more accurate hipfire than the Grendel? I thought a machine pistol should be very inaccurate compared to an assault rifle designed for accuracy and range...

Maybe due to the weight of the rifle?