Big Bill,
India and Pakistan have never produced 7.62x51 NATO ammunition.
They produced 7.62x51 ammunition, but without the certification that the ammo adheres to NATO quality standards. This ammo was intended for their service rifles and machines guns (MAG58 copies and MG42 copies).
The Indian service rifle is an unlicensed copy of the British service L1 series (itself a licensed copy of the FN FAL). It's a poor quality copy, and parts do not interchange with either the British L1 or metric FAL.
The Pakistani service rifle is a locally produced copy of the H&K G3 built on German machinery.
The reason for going into these details is that the FAL type rifles use tilt-lock breeches and adjustable gas regulators, and can tolerate a wider range of ammunition variables and still function reliably. The G3 design uses the Stecke hesitation lock, has fluted chambers, no gas pressure regulator, and is much less able to handle ammunition variables.
Hope that explains the different ammo results that have been reported.
Yes, the Indian surplus ammo is cheap, but I would much rather pay more and use quality European NATO surplus than the poor quality Indian/Pakistani stuff.
John