They did this because of the effective range of the rifle. The old ones didn’t have enough.
“They did this because of the effective range of the rifle”.
Bingo! Especially in Afghanistan. The M-4 is great for clearing buildings but after 400 metres it just hasn’t got the knockdown. Those jihadis are picking our guys off with mark 4 British Enfield .303’s from 1000 yards with open sights.