 A more reliable fit was made with four 20 mm (.79 in) Hispano Mk II cannons, two in each wing, but the weight was enough to seriously reduce performance.The Hispanos were designed for a rigid, engine based mounting and it was quickly found that the wings flexing in flight led to problems with the weapons twisting in their mounts as they fired, which caused gun jamming through misaligned shells.Changes made both to the Hispanos and to their mountings cured this problem.