I think the guys above nailed it. Start looking at heaviest stuff first: the chair and the firearm. Then start weighing everything to see what you need.

We don't take pillows, or hand warmers or extra fuel.

But then where we backpack, we use a bear can...so add two pounds right onto the bottom line.
Check our our website: http://www.backpackthesierra.com/

Or just read a good mystery novel set in the Sierra; https://www.amazon.com/Danger-Falling-Rocks-Paul-Wagner/dp/0984884963