Only a few actually made it into mass production, but around the world, there was eager development in the 1960s of low-pressure gun/missile launcher tanks, the kind best emphasized by the M551 Sheridan and M60A2. The Soviet designs have turrets that resemble”squashed” versions of the classic dome turret.
The impetus was how to extend the firing range of the tank. This arrangement was ultimately made obsolete by the development of better fire control (for western tanks) and barrel-launched ATGMs that could be used in conventional tank guns (for Soviet ones)
But they’re still an interesting footnote.