It neither works with conventional soldiers. Australian soldiers found their 7.62mm to be more effective against Vietcong than US,s 5.56mm. So Indian army took one lesson from Vietnam war that soldiers waste too much ammunition in full auto mode but did not take account of this experience? And maiming? Every country's soldiers are backed by Medics, average soldier does not take too much time to give first aid to an wounded soldier. And killing soldiers also mentally disrupts them. Completely faulty doctrine that's why IA reversed to killing round.
And in 2nd Sino-Japanese war also, Japanese soldiers, Japanese soldiers found 6.5x50mm Ariaska round to be less effective. If you think, lessons of world's other wars dont have any impact on us or we should never learn anything. You are absolutely wrong.
Every army learns from what they face. When they start copying others doctrine, is not called learning. Why you think multinational countries do undertake joint military exercise?
Indian army didn't took lesson in auto mode from Vietcong. When you dive into history of IA and compare it with present IA, you would find that from British era, importance has been given on accuracy rather then volume. Its the reason for our adopting SLR in the first place instead of AK after Ishapore 2A1.
Any army in world does learn from others regarding doctrine. They don't simply follow those doctrine, rather try to adapt them in their context.
A soldier is Siachen should not be necessarily armed like a soldier facing Pakistan in Punjab. M16A2 and M16A4 has 30 round magazines so how US soldiers fought while lying? How NVA soldiers fought with AK 47?
A soldier in Siachen is much less armed then his Punjab counterpart. But he in turn carries double the total burden of clothing and gear with him. In that case each and every gram of weight matters. M16A2 and A4 both does have 20 as well as 30 rounds mag. Now it depends on the soldier which he prefers. For your information a fully loaded 20 round mag of M16 weights 335 gms against a fully loaded 30 round mag which weights 480 gm. Now ask any soldier patrolling in Siachen or anywhere, which he would prefer weight wise.
Have a look at the firing position in both cases. In which position would you like to see yourself?
So I cant really understand, you first said box magazine of 100 round then you said magazines? You mean equivalent of 2 magazines or 60 rounds? An assault rifle is not supposed to fire like a LMG. And that problem is common with air cooled guns. If you guns to fire in sustained mode, give soldiers extra pouches of water. Try a water cooled gun. And still you have not shown any difference between INSAS 1B and INSAS LMG, that INSAS LMG weighs extraordinarily heavy like Bren.
I mean a box magazine of 100 rounds. INSAS LMG is made to sustain a heavy volume of fire for longer duration. For this purpose it does have an extra strong firing chamber and barrel, which in turn increases its weight.
INSAS's original version was not.
This is what known as development. M16 had been discarded as a toy by US army during Vietnam era when first introduced. Now its one of the most preferred weapon by many armies including India.