You are not completely wrong, however that is mainly the great war series. During the Settling Accounts series allot of the CSA equipment described could best be attributed to German type weapons.
Barrel Class
Confederate Models
Mark 1 (Great War) - Rhomboid barrel; 10 man crew; two 50mm guns, 3 machine guns.
Mark 2 (Between the Wars) - More familiar shape, with rotating turret. Crew of 5-6; Estimated 37mm gun, 3 machine guns.
Mark 3 (Second Great War) - Upgraded version of Mk2. Crew of 5; 50mm gun, at least 2 machine guns.
Mark 4 (Second Great War) - It held a crew of 5; mounted a 75mm cannon, and had 2 machine guns.
Mark 5 (Second Great War) - The latest Confederate model, it sported a low hull, superbly sloped and thick armor that increased crew survival rates, and a high-velocity long-range 4.5 or 5-inch gun. While superior to all US barrels, there were too few to stem the tide.
Unites States Models
Mark 1 (Great War) - 18 man crew; one 50mm gun, 6 machine guns.
Mark 2 (Between the Wars) - Nicknamed the 'Custer.' The Custer was advanced for its time. It carried a crew of 5; mounted a 37mm gun, and carried at least 2 machine guns. The prototype Custer carried a 50mm gun.
Mark 2.5 (Second Great War) - This barrel was developed to be deployed as quickly as possible to meet the challenge of the Confederate Mark 4. It consisted of a Custer barrel body with an upgraded turret. It carried a crew of 5; and mounted 60mm gun, at least 2 machine guns.
Mark III (Second Great War) - The American response to the Confederate Mark 4. It was powerful, heavily armored with "perfectly" sloped armor, and carried a mounted 90mm cannon along with three machine guns. Deployed shortly before the invasion of Kentucky and Tennessee. This was the first United States barrel that outgunned the Confederates' best barrel.