"
They refused to give me the thread pitch and inform me that I have to send it into a service center! I can't believe this...."
You were working with the fire control-the trigger assembly, right?
How do you spell "
Product Liability"?
It is not unusual for firearms manufacturers to refuse to sell replacement parts for certain assemblies and instead, require the firearm to be returned to the factory. You can thank the insurance industry and this country's legal system for that.
Customer service probably doesn't know the thread size for that screw, just the part name & number.
Bruce