Where the hell do you learn that you can use Afterburner Gum to disable those stupid and almost invincible (considering that I don't have any energy/heavy weaponry yet) turrets?

Yeah, I read it in the wiki somewhere... That's not "in-game" ...
Especially since I read that AFTER I set up the alarm System and probably dooming the whole village of Praetora or something.
Probably lost several hours of gameplay because I had overwritten the important savegame and the closest one is way before that mission.
Is there any in game story, info, MacGuffin, Tutorial-whatever that tells you that?

you can't learn it because it is a bug.....or why do you think you don't earn EXP from doing that...or why is it even
possible to use drugs on an mechanical device?

Thank you, that makes more sense that anything else...
So, next question :-)

HOW am I suppose to stop those stupid turrents from eviscertating me and the soddlingly tribal village with my AK47s?

They are nasty things. But they are not mobile and can't aim. Now it depends on your weapons skill and AP
(i confess i used the try and reload method) Take cover.. one shoot than retread. Funny thing if you have a brawler he
hits more than your sniper.
There was also the rumor that you could steal their ammo and than just wait till they run out of it...never tried.

Thanks, I managed to steal some ammunition from the top side turrets but underground I'm getting wasted.

I'm not having anything armorpiercing yet. 95% shoots don't connect or deal 1 damage.
Criticals "pass their resistance" and do 5 damage while the turrets have 300 hitpoints.
Even the melee Attacks don't connect.

So this isn't really working out. Not at all...

I can't go back to base to buy me some piercing melee weapons or special ammunitions.

That's what I hate about the "classic" games, you develop a working strategy than finally begins to pay off, then the game gives you a new foe with damage resistance and your whole strategy goes haywire.

Tough ones i know.
And the only 1 damage is normal. The only way for this to work
(if you don't have unlimited ammo) is with a good sniper and aimed
shoots at their sensors....and the hope for a critical...hence the
try and reload method....
Thats also one of the things that makes Fallout legendary....
every enemy has an weak spot....and if everything else fails (no
proper savegame before the battle) either start new or use
the savegame editor (after that you can reset the old stats).

i think switching to realtime and using melee weapons worked for me (to save ammo)

Thanks to you all,

restarted the game, having a badass main character with an hunting rifle and a diamond spear as main weapons.
He might only have Endurance 2 but the rest of his SPECIAL stats are awesome, I eliminated all the turrets with almost no damage taken. Let's see how long I can go with this character.

Are you playing the game using any of the community Patches, or un-patched?

No Mods/Community patches thus far, my second play through will include community patches.