I'm pretty sure rifled makes HESH slightly better because it relies on how spreadout the explosive patty is to be more effective. I'm not sure about standard HE but I doubt it matters much if any but rifled is worse with higher chamber pressure as they'll wear down on the linings faster and also make gun launched AGTMs more complicated.Does it really make HE performance worse though? British 120mm rifled HESH rounds suck in terms of accuracy vs Soviet smoothbore 125mm HE-FRAG rounds.
I think using a rifled gun is a big mistake. Look at what the Soviets did with the T-62. They rebored the gun eliminating the rifling and got a higher caliber smoothbore gun.
Dedicated ATGM carrier on the same chassis would be consistent with previous vehicle families.
They had access to 125mm guns that are anecdotally far superior to Russian and Ukrainian 125mm guns. If they chose the 105 despite that then there is probably a very good reason.My guess is they just used the Type 15s autoloader mechanism. Maybe with slight modifications. To speed up development.
And the Type 15 was probably supposed to be an inexpensive tank so they started with previously available ammo from Type 88.
It is messed up to use it in a much more expensive tank like this though. If true.
Before someone takes this the wrong way do note that Chinese 125mm production was at a much smaller scale of production than Soviet production. Its noted in documentaries that they had a very high standard for tolerances.They had access to 125mm guns that are anecdotally far superior to Russian and Ukrainian 125mm guns. If they chose the 105 despite that then there is probably a very good reason.
If the tank is designed for tank duels at all then I tend to agree rifled gun is a big mistake. Now I'm thinking tank duels is entirely out of the equation in the design, there're simple a plethora of means to deal with enemy tanks that it is better to design a tank focus on infantry support and survivability against all threats.
Fwiw fatty agrees with you, reading between the lines Fatty probably think the type-100 system is meh
Edit: If tank duel is still a thing there's always the Type-99B and it's possible future variants, but such a thing will not be as strategically mobile as the type-100 system, thus less relevant to China's defense requirement in the future.
China could have made a type-99B with all the bells and whistles of the type-100 but they didn't, it kind of shows what China thinks it's future priority is at