Firstly, the Indians didn't 'mess' up the T-90 Fire ctrl system. They tried to enhance it by
fitting it with a thermal imaging system that would atleast double the gunner's night targetting range.
Note the above quoted article gives the French thermal imaging system a range of 3km while the default thermal imaging on the T-90S for night vision
is half of that for the gunner and 1/4th of that for the commander.
I am unable to get the exact specs on the Catherine TI system from independant sources, but I will try for the same.
Compare this to the night vision ranging capabilities on the M1A2 Abrams and other major tanks like the Challenger and Merkava:
I think its about 2500 to 3500 meters for the gunner's target identification; correct me if I'm wrong.
Default T-90S FCS & Night Vision:
The T-90S has the 1A4GT integrated fire control system (IFCS) which is automatic but with manual override for the commander. The IFCS contains the
gunner's 1A43 day fire control system, gunner's TO1-KO1 thermal imaging sight which has a target identification range of 1.2km to 1.5km and
commander's PNK-S sight.
The gunner's 1A43 day FCS comprises: 1G46 day sight/rangefinder with missile guidance channel, 2E42-4 armament stabilizer, 1V528 ballistic computer
and DVE-BS wind gauge.
The commander's PNK-4S sight includes a TKN-4S (Agat-S) day/night sight which has identification ranges of 800m (day) and 700m (night). The driver is
equipped with a TVN-5 infrared night viewer.
Source
So there's nothing wrong with the T-90S basic config and the Indians didn't 'mess' it up. Its a phase of trial and tweaking. The temperature
problems with the catherine systems will not and cannot halt the IN Army T-90 program. I'll be the first to post links when a solution is found and
incorporated.
As for the faulty ammunition, again there's nothing wrong with the Russian supply, and the Indian ammunition which is clearly an attempted
improvement over the Russian supplied 125mm bore ammo also has climate issues.
IMHO this is all a part and parcel of trying to tweak a system for maximum yield and setbacks are probable. Nothing wrong with Russian equipment AND
nothing wrong with trying to build on it. End of discussion.