The treaty is binding between those who signed it. While the 1899 is the origin, I believe it might be carried forward through other conventions and case law also.
https://en.wikipedia.org/wiki/List_of_p ... 9_and_1907
The last column shows that India, Pakistan have acceded to it in 1950 and China has in 1904.
While the face of modern warfare and technology has indeed changed, nations still by and large adhere to treaties that they accede to. Which often creates quixotic effects (eg completely legal to bomb, shell, harpoon, knife or shoot enemy soldiers with a non-expansive bullet, it isn't legal to do so with a expanding bullet. A civilian or a policeman can use it blithely, while or an army can use it legally against terrorists or non-state actors/
LeT/Hizb/isis etc but not against another signee (China, Pakistan). Germany complained about Britain and had it upheld. Another irony - Ardagh (of the Ardagh-Johnson line fame in Ladakh ) argued to keep the Dum-Dum legal to use against the natives (ie Indians) but was overruled, while independent India acceded to it). Legality is not about where it is used (inside the territory or out) or how (in defense or in offense) but by who and against whom.
The previous comment 2nd link talks about element in the US army arguing to use hollow points (the US did not sign that section of the treaty, but still chose to follow it ; there is an international case cited also) and also arguing the age of the treaty, but AFAIK, it hasn't followed through.
Apparently hollow points can be theoretically created which do not expand (thus legal !) however one source said that these aren't seen as useful as damage inflicted is less (there's lots of similar nato studies on yaw/tumbling etc) and as increased penetrating power (eg against body armor) would push to use a different bullet. (penetration vs tumbling in the body are somewhat cross-purposes for a given caliber)
While you may be right that India may be willing to contravene legality in operation and heat of war, this would be much more detectable from the point of manufacture/issue, far before war; I wonder if India would choose to do so.
Having researched up a bit on the legality above, though, I'm still interested in your thoughts.
I know there was also discussion about using the same formations against terror and war (eg kargil) and that this was not preffered for various reasons.
Also, there could be other ways to get to more lethality in the same caliber (eg US moving to M855A1 from M855A
https://www.americanrifleman.org/articl ... cartridge/), but this may also require much more data and doctrine on how they are meant to be used, distances of typical engagement (eg ~300 m), training, volume of fire etc. I know you touched briefly on some of them. Was wondering if it was permissible for you to elaborate in Indian context
