Don't over-complicate it. What the IA wants, and what ARDE has delivered is a multi-cal that overcomes certain logistical issues. Today the IA has 2 assault rifles- the INSAS is it's standard assault/battle rifle but for troops in CI ops it uses the 7.62mm AK series. The reason for the AK in CI is well known- in close quarters the 7.62mm delivers a "punch" (kinetic energy) down-range that is devastating, 5.56mm has been known to maim/wound but not kill. In a "close" fight you want to put down an enemy and put him down for good. The 5.56mm however delivers better range and accuracy so is the IA's preferred "battle round"- i.e. what it would go to war with.
The idea behind its multi-cal requirement is to have 1 common rifle that fields both the 7.62mm and 5.56mm calibres so when a unit is in CI ops they will field the 7.62mm, when they return to their bases and reorient to conventional ops their rifles will revert to 5.56mm. No need for extra training or a separate logistics chain- one rifle replaces 2.
Reading a lot about rifles here, I wud lyk to share force's actual idea and desires about rifles.
By my own field experience in CI ops, I would like put lights on few issues with which we are facing daily-
1- X-95 aka tavor is the worst rifle considered by paramilitary personels,
Reason is accuracy problem since barrel is too close to the body there is too much bubbling. Also mechanism being closer to ear makes too much sound which inturn creates concentration problem and also headache for long hours of firing.
Also being it of fibre body it is prone to break or damage which leads to COI in armed forces therefore nobody wants to carry it.
2- Multi- caliber is just not so useful concept in field. U don't change weapon's barel in field. It is done by trained armourer in Central Weapon Store.
3- Also Insas cost Rs 8000, Bulgarian AK Rs 6000, and Tavor Rs- 46000
4- Biggest nightmare for a soilder in field is jamming of rifle. This problem is too much with Insas and to much extent with Tavor ( X-95). Here rules AK with no jamming problem at all ever. Thats is why out of worlds 10 million Assault rifles 8 million are AK series (source- wiki)
5- we all want AK's in huge number. They are cheap easy to maintain best weapon on field.