In the update 1.5 artillery received various nerfs. The most notable one is to Conqueror Gun Carriage. Shell velocity of both HE rounds got reduced by 9% which resulted in something that nobody anticipated: maximum firing range decreased from 1000 to 820 meters and shell trajectory changed, becoming more steep. So effectively CGC was buffed by being able to shoot behind cover and hit weak top armor of enemy tanks even more effectively. One of WG community managers stated on RU forum that this is not a feature, it’s a “bug” and it will be fixed. Maximum range and trajectory will be changed back while shell velocity nerf stays.
Source: wot express, skillfully translated by Robopon