I was actually wondering how strong Guyver armor is. It seems small firearms such as pistols or 9 millimeter's don't seem to penetrate it. Even zoanoids as strong as gregole don't seem to be able to tear into it. So just wondering how strong the armor itself is. Can the armor with stand an armor piercing AP shell?

 

https://en.wikipedia.org/wiki/Armor-piercing_shot_and_shell

I think it can. I have only seen weapons such as Guyvers work. Like Thancrus' blades and the like. Or a Zoaloard can take them down too. Depending on what they utilize.

This is where it gets complex.

 

The Uranus in Guyver armour (though for them it's not called that, no idea what the official name is then) but they were said to be 1/10 the strength of a Guyver. 

 

As a symbiotic relationship the Guyver armour ultimately is only as strong as its host bio-boosted potential. 

 

The Guyver armour without the Control Medal is even scarier and can merge creatures together, so if you shot it, I doubt shooting it would help you much and you'd be lunch very soon. The only thing holding that back is it gains a level of smarts from what it absorbs and might be smart enough not to eat it's food source. In saying that the only thing that would stop that level of danger is another Guyver or Enzyme Zoanoids.