if you find 40 better then your shells would have been landing behind the target, a setting of 40 tells me that your firing at extreme range, the RN CL line suffers from a ballistic trajectory that I only rivalled by Atlanta.
in short, the longer the shell is in the air the slower it gets, the 43-45 settings are best for around 5-10k, if you fire from further away you will need to increase the lead time.
TBH mate, you really should be much closer than the max range of the ship, you need to keep out of sight, get in, hit them and get out fast, if you sit back firing at max, every 16in gun on the enemy team will zero in on you and you can kiss your arse good bye
BigD got a reaction from deadshine in UK Velocity/Height Table