In the Campaign Book: Hades, the IS-5 B "Vladmimir Lennin" shows that the 252mm Field Mortar has the "A" range which indicates that it is a Artillery weapon. However, in the Weapon Abilities description on pages 26 and 35 it doesn't state that it has the "Artillery" special weapon ability. My guess is that this is a misprint, but I'm wanting to get others opinions on the matter.

A stands for artillery like c stands cor close combat weapons. It is explained in the actual artillery weapon rules in the core book. The weapon doesn't actually have to have the artillery special rule. It just needs the a designation on the stat line.