A Battle Rifle , Designated Marksmen Rifle, Sniper Rifle, Long Range Sniper Rifle, Anti Material Rifle are all completely different from the ground up. The bullet calibre is only part of the equation.
Very True ....But with advancing Technology the lines between all these platforms are becoming increasingly
blurred.....
For example a modular weapons platform like
SCAR H can serve as a DMR, Battle Rifle & Assault Rifle (with slight modifications).... For DMR it would need a heavy barrel and specialized optics & ammo, for the rest of the two the standard pencil profile barrel will suffice ....All these changes can be done at user level and not armourer level..
Also, SCAR H can be easily converted to a very very high class
multicaliber platform (7.62x39, .300 blackout, 5.56x45) , which can satisfy all the requirements of country like India.
http://www.defensereview.com/handl-...62x39mm-russian-ak-47akm-300-blackout-300blk/
I consider the INSAS LMG closer in concept and execution to the Marine Corp M27 IAR(Infantry Auto Rifle), than as a DMR as mentioned by somebody.....depends on use and perspective ...
I don't believe that the LMGs or MMGs won't be required just because of 7.62x51 rifle adoption.
The purpose of these is suppression and very high rates of fire, for which you need a Quick Change Barrel and belt feed or 100 round or more Pouch magzines...which is not possible with the standard rifle.....
SNIPER RIFLES - I believe in two categories of sniper rifles (both in Bolt Action Only).....The
Long Range Sniper rifle should be in .336 Lapua Magnum or Norma Magnum.....
The
Short Range Sniper can be in 7.62x51 , with specialized ammo, optics and bolt action (although calibers which can fit in same magwell size like 6.5 Creedmore and specially 6.5 PRC beat the 7.62x51 in both range and ballistics by a long way).....