So, during the late 1950s, the UK experimented with a heavy AA gun codenamed "Green Mace".
It was a very capable weapon, and was only really canceled due to the introduction of early SAMs.
During testing, Green Mace apparently demonstrated a fire rate of 96 rounds per minute, which is mind blowingly high for a 102mm heavy AA gun. The gun itself had a range of about 4-5 miles, and fired folding fin discarding sabot ammunition. It should however, be noted that the weapon required a 15 minute reloading time, alongside 2 trailers for ammo and power.
Now, 3 what-if questions:
1. Could Green Mace have been used as a heavy anti-tank gun? How feasible would this even be?
2. Could Green Mace have been mounted on a tank (centurion on conquerer hull)? Presumably, if the something like the FV4005 exists, then something like this could too. The only real problem I can see with this is its constant need for power and ammunition.
3. If approved and put into service, how could this effect Soviet armored/military doctrine? Would we see more Soviet heavy tanks or a earlier helicopter gunship, or something entirely different?
I can't see a weapon like this having a change in the strategic balance of power, but considering it fires 102mm discarding sabot ammo at 96 RPM, it seems like a pretty good system on paper.
Green Mace^
(stats and picture from Wikipedia)