No, Hornady does not use an 8-inch barrel for its advertised ballistics for Critical Duty ammo. Hornady's advertised ballistics for Critical Duty ammunition are generally based on a 4-inch barrel.
Critical Duty is designed and optimized for use in full-size service pistols, typically with barrel lengths around 4 inches or longer, to achieve consistent performance and meet FBI barrier penetration standards.
For comparison, Hornady's Critical Defense line is optimized for short-barreled concealed carry firearms, typically those with barrels under 4 inches.