Tried setting it at the highest possible damage higher which would be 310 from a pump shotgun didnt work. Tried setting it just above standard armour value at 20 didn't work X_X this really is testing my nerve
Is it not working because your character takes near-lethal damage every time a shot lands, or not working because your character is still taking some small amount of damage? I'm imagining that you're seeing hits get through, causing a small amount of damage that causes you to start bleeding, which then does a lot more damage over time...
You can't block every attack with armor, it just doesn't work that way. Armor doesn't subtract damage from an attack, it shrinks the damage from an attack, and there's a maximum amount it can shrink an attack by -- to 1/36 damage, specifically. That will nullify low-damage attacks from people punching you or scoring glancing blows, but a solid shotgun blast doing 200 damage is still going to get 5 damage through, even through the best armor in the game. For reference, it takes 100 damage to kill you.
At 15 armor you have the same armor as a M1 Abrams tank. That's about as good as you can possibly get in LCS, though a bit of extra armor above that will help to prevent agents with high skill in assault rifles (which ignore some of your armor) from nullifying your armor. Still, it won't take much to reach maximum effectiveness. Your experiments are probably all equally maxed out, with both the 20 armor and 10000 armor items doing the exact same best-possible-armor-in-the-game thing. Tanks will ignore about 20 armor, but they also have a base damage range that starts at fifty times your maximum health, so so a 20mm shell from the main cannon will one-shot you even if you have infinite armor.
Ultimately, if your aim is to be a one-man wrecking crew, you'll need to do it with more than just equipment: You need skills on your founder. The most important ones are dodge skill (based on agility), which will let you avoid attacks entirely, and first aid skill (based on intelligence), which will let you stop bleeding from attacks that do get through your armor. A weapon skill, probably agility-based, is also important. Even without armor, a lone high skill founder with a sword or assault rifle can fight off mid level enemies pretty much forever without taking a scratch (or until ammo runs out, in the case of the assault rifle).