I'm sure someone has covered this before, but my jedi search powers are not good enough it seems.  I did my due diligence but could only find bits and pieces in various threads regarding this topic.

My brother is buying 40+ acres in central CA, and we thought it would be great to have an AR we could go hiking with.  Something very light weight, used for plunking, possibly protection from coyotes/varmint hunting/etc.  Something that doesn't need to be pretty or endorsed by any operators.  Just decently accurate (think 200 yds), and the most critical factor, light as a feather.  

I was thinking a 14.5" barrel would suffice, or a pencil profile barrel (beggars can't be choosers these days).  I can get my hands on a 14.5" plus flash hider.

I don't mind plastic grips (prefer Magpul MOE to the retro style, and I can add rails to that).  What receiver/gas block/BCG/Charging handle (this already should weigh nothing)/upper parts would you recommend?  Is there any company/certain parts that have dedicated to a lighter weight build?

For lower parts, is there such a thing as a carbon fiber lower?  Which stock/buffer tube/etc would you recommend that is decent, and light?

I already have built one AR from scratch, and another lower from scratch, adding on an upper from one of the vendors on here.  

Thanks in advance for any constructive answers.

Most will recommend you stay away from carbon fiber lowers since BM's are notorious for cracking. Sabre Defence has a CF lower out though I've seen no reviews of it.

Stick with a semi-auto bcg, any std charging handle, MOE handguards are good, Old style CAR stock.

OR get a cavarms lower, that'll take care of a lot of weight!

I've never weighed it, but I built up a very lightweight rifle from scrounged parts using a CavArms lower I bought during the Cavaid program.

I used a $50 blemished flat top upper and a M16A1 pencil barrel I found at a gun show for $75. I cut off the front sight tower and used handguards and a gas tube I had laying around and put in a new RRA BCG I found on the EE for $150. I put on a $35 YHM cantilevered riser mount and a $150 Weaver V3 (1x-3x). This thing shoots dime size groups at the local 75 yard range and it's light as a feather,

The Cavarms lower came assembled, but I did send the trigger group to Bill Springfield for one of his $35 tune-ups. Well worth it.

I'm curious now. I'll try to find a way to weight it accurately.

Cav Arms lower, Carbon 15 Upper assembled with a 16" Superlight Barrel = 5 lb 1 oz without magazine.  

What's up with that gap in front of the magazine? Is that how they all are?

nice.  i just weighed both my AR's and they are 8lbs even, each.