All the Indian 125 mm FSAPDS/APFSDS rounds that I know of. This is a fairly limited account due to the lack of accessible documentation & reliable sources.

(1) "Steel Core" (1984–1993) — Appears to be a copy of the Soviet 3BM15. Same period coincides w/ 105, 120 Mk.1 & 125 Mk.1.
(2) 125 Mk.1 / AMK340 / Soft Core (2A) — Developed during the same period as a concurrent alternative to the 3BM15 copy. It featured a WHA 14:1 L/D monobloc long rod and was subsequently productionised.

Since the last thread had a good reception, I will be somewhat continuing the lore with the various ammunition types made for the Arjun over it's development period till date.

https://x.com/thugner101/status/1927693510821466423?s=19

As discussed earlier, the first GSQR 326 of 1974 had asked for a 2nd gen APDS (using tungsten heavy alloy core) in conjunction with HESH, Smoke and a 3rd gen F&F gun launched ATGM for a 110/115 mm rifled & smoothbore gun (later removed and rifled was finalised).

A thread on some pictures of DRDO/CVRDE's Arjun MBT prototypes I found. Total 12 were made between 1983 and 1989 but I haven't got a positive ID on each and every one of them so it will be limited. Will update in the future as new info surfaces. A schematic chart of the Prototypes with dates and stand-out features. Dropping it here for general reference.

A thread (in parts) on the sights and fire control system upgrades of Indian T-72M1s, T-90S's and BMP-2s over the years. Won't dwell much on the abandoned plans, just what is done and present. The original T-72 upgrade under Project Bison by CVRDE/BEL included: DRAWA-T FCS using El-Op's TES 2nd gen imager, biocular displays, CNR-900M VHF radio sets, R-174 Mk.II DCH comm sets, ALNS land nav system, IFDSS set and ERA Mk.1 tiles.