What could be the point blank range for 125mm gun ? for a 155mm i know its 1.5km for a small arm its few inches..
So, can it be from 200-500ms ? probably..
Point blank range will be from 500m to 100m and below, but it can't be too close so the test gun won't be damaged.
However as You provided, the ammunition used was not modern, so the results are not very impressive, I seen similiar tests done in Russia on T-90A turret without ERA, I also seen some footage from German tests, and from American tests but without any descriptions so, nothing can be said about them.
Most Armour in the world are not tested against latest developing ammo, T-90S was tested against BM-42 ? or latest Russian Ammo its not publish so one can assume again that its not also full prove against latest US and German ammo..
Not everywhere, tests are performed with avaiable ammunition, so while Germans and Americans definetly tests their armor against their ammunition, which is currently the best out there, other countries sometimes needs to perform tests with obsolete ammunition. And this is normal, the problem starts when someone starts to claims about superiority of one armor type, that was not tested against most modern ammunition. It is even dagerous because it puts too much confidence in troops, they perhaps will take too much risks, and when something bad will happen, You know how public, general staff, politicians could react, in the end someone might say that this is a fault of designers, and something might end wrong.
This is because designers, the engineers designing this stuff mostly are not talking big things, this is what PR guys are doing, but PR guys and later fanboys might say too much, and as I said above, many bad things might happen.
This goes against most - most other tanks, we only assume, regarding Arjun at least officially we have idea on range, About the and ammo used took little time and the layout of Kanchan gives us a hint it is a frontal test..
Yes it gives us idea about protection against older or obsolete types of ammunition.
From range i can also say, the penetration is not just 500mm of RHA coz the shot is taken from much closer range from which i can conclude that the penetration level is higher than just 500mm of RHA..
Not exactly, I heard that APFSDS penetration levels are preaty steady, of course from the closer range penetration will be a bit bigger, but the question how much? Ahhh this is tricky thing to guess without a tests.
The HEAT round of 106mm RCL is 620 mm of RHA, these test were conducted more than a decade ago..
It is not something really special. The UK/US Burlington in the second half of 1970's and beggining of 1980's was estimated to provide protection against HEAT at the level of approx ~700mm to ~900mm RHAe.
As for protection against HESH, even very simple spaced armor provide protection against such ammunition, due to it's working mechanism it is very easy to defeat it.