Pakistan Army is using POF delivered G-3 rifles. The weapon is actually from a rifle category, best suited for aimed shots. It has a longer range. but who needs long range now, and fire aimed shots. Also rifle is poor in kicking back on Shoulder. All over the world, Armies hav shifted to lower calibre: 5.56 mm. The advantages of 5.56 mm calibre over 7.62 mm (as in G-3) are:
1. Lower calibre means, lighter barrel: so lesser weight of the weapon.
2. Reduction in calibre means ammunition weight is reduced per round, so more bullets, may be carried. Thats why, mags for 5.56 calibres are 30 rounds mag instead of 20 rounds.
3. Lesser propellent in cartridge case, means low weapon recoil: thus better handling qualities.
4. Better handling qualities means, weapon is good in CQB (close quarter battles).
5. Pakistan Army is mostly fighting war in hilly region, where engagement ranges do not exceed 1500 meters. Thus '5.56' is ideally suited.
6. As weapon and its ammo is light weight, so soldier may carry weapons for longer duration, distances, causing less fatigue.
So i think, Pakistan should switch to 5.56 mm calibre.
My vote is for Colt M4 Carbine ( USA).