“Turn in flight. And follow a laser beam. Or guide in on a heat source.”
Why is any of that necessary. With a HEAT round, if you can see it, you can kill it - well over 90% accuracy. So who cares if a missile can be guided...the tank crew guiding the missile is going to get blasted to hell and back while they’re playing Atari with the missile. Just shoot and kill.
As far as range advantage goes - yes a Russian anti-tank team hiding in the bushes can really reach out and touch someone from a long distance...and be more or less concealed while doing it. Even the TOW on the Bradley allows the vehicle to be in a hidden position. But range gets you very little when you’ve exposed the entire tank to launch out of the main gun. I don’t know the speed of these missiles, but they are subsonic, or less than 343 meter/second. So, they have to fly and be guided for 11 seconds...just to get out of the effective range of an M1. In a tank battle, that’s an eternity - using HEAT or Sabot, a tank will have engaged 2-3 targets in that time frame.
If terminal guidance is so superfluous, why then is it considered such an attractive feature of the Copperhead CGLP, as well as several models and generations of British precision guided versions of both 120mm and 81mm mortar rounds?
It's one more potential tool in the loader's rack. And too I wonder how far we are from homing antiradiation missiles for tank main guns. The Germans were working on something along those lines as far back as a decade ago, for naval use, but then too their naval equipment included the MONARC concept for a frigate-class warship equipped with the 155mm gun turret of the SP Howitzer 2000.