In this image Shatrujeet has mentioned that this weapon is not M16 but actually it is
AR-18 assault rifle.I hope someone from Shatrujeet would correct it.
In fact I'm little surprised we actually had this in our Arsenal.This weapon is often called 'Poor Man's AR' as it was cheaper to produce this (in some cases,even cheaper than Kalashnikov) because majority of parts in it are made by stamping procedure (even hammer is a stamped sheet) except for several key parts such as barrel,bolt,gas piston,springs,trigger and parts of trigger group,magazine lock,bolt carrier,firing pin,furniture such as handguard and pistol grip,receiver holding pins,gas block and front iron sight post and cocking handle.
Japanese Self Defense Forces' Howa rifles (later 5.56 x 45mm NATO variants) are actually licensed produced variation of this weapon with some modification.