The guns were fitted with Magslip electrical data transfer from Predictors AA Nos 3, 5 and 10 and were probably used initially with GL radars and UB 10 18 feet base optical height and range finders. AA control radars evolved rapidly. The gun was laid and fuzes set by pointer matching, it is unclear the extent to which advances in 3.7-inch fire control were applied to 4.5-inch. During the war Machine Fuze Setter No 10 was added, This improved the rate of fire from 8 to 10 rounds per minute and raised the effective ceiling to 34,500 feet.