Now this, this is fun.
The HT9A7 SMBT (Secondary/Support Main Battle Tank) is a tank based off the gun-launcher tanks of the 1960s and 70s, such as M60A2 or MBT-70, and is basically designed to capitalise on Anemonian armoured doctrine and make it as potent as possible. The Anemonian armoured platoon consists of five tanks, with two mobile groups of two tanks and a single tank for support duties. SMBT is designed to take over the role of that 'fifth' tank, and as such, is optimised for three things, all support duties; killing tanks at long range, lobbing large HEDP shells and the ability to engage helicopters (to some extent).
And it can do what it's designed to do. Long shell casings and a 150mm+ gun launcher mean it can launch big rounds and missiles with big warheads. And the armoured 20mm cannon remote weapons system gives it the capacity to engage aircraft; stick one of these on the end of every tank platoon, and suddenly, things begin to hurt a lot more for the enemy opposite.
The gun is still relatively long barrelled to make sure it can still fire APFSDS shells if it *needs* to, but it's not normally loaded up with them.