First some background :
Indian Armed Forces today utilizes the HE-36M hand grenade manufactured by Ordnance Factory Board in India. This grenade finds its origin in Mills Bomb, a popular name for a series of British Hand Grenade made by William Mills in 1915. The grenades were used in WW 1 and WW 2, of course along the way it underwent various modification in its design and features. Most notable among those were the per-fragmented pineapple like outer shell of the grenade which aids fragmentation and increases lethality. The British and a lot of other countries gave up the use of these grenades in the 1980s. However, India being at least a decade or so behind western militaries, continued using it. This however had some pretty bad outcomes. There was a spate of accidents involving the 36M grenade, leading to questions being raised about the safety of the grenade. MoD persisted with the criticism for a while then finally in late 80s-early 90s, the OFB was roped in to develop a new grenade.
Well let's just say OFB tried. Let's leave it at that. As the OFB was going nowhere and MoD was increasingly growing impatient, DRDO jumped in to help OFB. This was a fantastic move as ARDE, a lab under the DRDO, had around that time successfully developed the Pinaka MBRL. The development of the Pinaka needed a explosive with reduced sensitivity, to prevent accidental ignition. This was the same explosive fuel that the OFB would use to make a "new" grenade named HE-36M.
The HE-36M hand grenade, as the name would suggest, is a evolved variant from World War-2 of the original 36M Mills bomb. The design, both internal and external, were the same. The only differences were the explosive fuel, and a new casting method for the grenade components. This greatly improved the grenade's reliability, safety and shelf life. This HE036M continues to used/produced in bulk in India.
There are three version of this grenade in use :
A. Drill grenade : This is painted with white colour and has five holes in it and is used for practice of grenade throwing.
B. Instructional : It is dissected in half , in order to explain and teach the internal mechanism ,working and various parts of the hand grenade.
C. Live : This version is painted with light and dark brown colour and there is a red colour band painted on it , signalling that it is live and dangerous.This grenade is the armed version which is used in live combat.
That little exercise in the 90s proved to be an eye-opener in terms of munitions development in the country. As the HE-36M was adopted in service, many munitions soon followed. For example :
The HE-36M based rifle fired grenade :
Specs :
Ordnance Factory Board
For T-90 tanks :
Stunt grenade(well sort of) :
And finally, a real new grenade, not a copy of somebody else's design :