A single weak spring was replaced with two stronger springs because there was not enough force to fully close the bolt sometimes, more so with any kind of dust or debris in the breach.
The tolerances on the gas parts was improved significantly. Loose gas parts would result in the bolt not being pushed back all the way resulting in spent casings failing to eject.
Tolerances on the bolt parts improved significantly.
Added firing pin retention pin to the bolt to stop the firing pin falling out of the bolt when disassembling.
Bolt and gas parts anodised to prevent buildup of carbon which would cause the bolt to size up.
The shell ejector was improved significantly. (Would fail to eject spent casing from the breach when a bit of dirt/carbon was present, resulting in double feeds)
The firing pin upgraded to better quality material as it would break often and easily.
The cocking handle redesigned to defect casings away from the ejection port as they would often bounce back into the rifle after being ejected.
Cocking handle strength improved as it would break/fall out.
Magazine release catch guard added to prevent your mag falling off when patrolling with the weapon in a rested position again your body, also made the magazine port a lot less slippery so mags don’t drop put of the weapon AR15 style. (It was deemed irresponsible for soldiers to keep losing their mags)
Bayonets catch improved to stop your bayonets falling off.
Magazine material changed from aluminium to steel as they would bend if you sat on them causing rounds to get stuck.
Magazine spring significantly strengthened as it would be worn out easily, soldiers would be told to load no more than 20 rounds to stop them being worn out too quickly.
Plastic parts would melt when coming in contact with the issued insect repellant.
Plastic parts would crack in cold weather
Plastic parts would fall off in hot weather (crap glue)
Handguard would melt after fring too many rounds
Handguard gas part inspection flap would pop open when firing (has always been an issue on all variants except A3)
Handguard not free floating (not fixed until the A3)
Susat sights could sometimes leak tritium gas… apparently. The amount of times I’d see people drop their rifles on their sights and still be able to shoot straight, but of you sneezed on it they would lose their zero.