From: Akron, OH
I found some data in David Isby's Weapons and Tactics of the Soviet Army, it puts the TOW at 90%, 105mm APDS at 1,500 meters 61% gives some penetration data also..
Says the Soviet 125mm HVAPFSDS at 2,000 meters is 46% to hit (stationary target and shooter)
It has more data on the 115mm gun, with laser rangefinding and without...
It does have Soviet ATGMs too, 87% for the Sagger at 2,000 meters for example. It appears the later improvements made the missile easier to control while being shot at, faster, better control at shorter ranges, and improved warheads. My guess is the new ones require less training time also. Regardless, long range shots if you can see the target, the target does not see you, is stationary, pretty much are going to hit regardless of which ATGM it is.
Put some smoke on them or you, shoot at them or their general area, and/or move should greatly reduce their accuracy.
I did see a combat video of a TOW I think hitting a Syrian tank recently. Time seems to slow way down as the missile moves downrange...