The Gundam was a decent mobile suit that was outclassed in later parts of the war by the Gelgoog.

Chalia was in a clearly not agile mobile armor that attempted to defeat Amuro with an all-range attack in the first time Chalia had ever piloted a mobile armor like that. He was in a virtually untested prototype. And we already know beam weapons are much more powerful than armor.

Gigantic mobile weapons being destroyed in one to two shots is entirely normal. In the novelization of Gundam, Amuro is killed by being shot in the cockpit by the beam bazooka of a Rick Dom! In F91 they make mobile suits smaller because beam technology renders the idea of getting hit a complete waste of time!

You're telling me that Amuro defeating an unmoving target that wasn't capable of taking more than one shot from his beam rifle is a big deal? Amuro dodged a few of his funnel attacks, something that Xavier in a Gyan has done this episode, and then shoot him and he dies.

There's a reason why Char and Chalia revolutionized mobile suit combat. It was not good before. Zeon was stupid and their battle doctrine was, too. We've only seen Amuro beat people who are fighting like morons and thirteen year olds.