Grey Ghost Precision

GGP Cornerstone Lower™

(11 Reviews)
Current Stock:


Cornerstone; “the chief foundation on which something is constructed or developed” When you want to start your AR build, the lower is the starting point. The fit and finish of our cornerstone will prove to you that you have the right beginning to a reliable and strong AR build. When coupled with our Grey Ghost Precision uppers, the match is very hard to beat.

Machined to tighter than Mil-Spec tolerance, the critical tooling dimensions are held to within +/ - .001"
Machined from forged 7075-T6 Aluminum
Black Hard anodized with a surface hardness of 60 Rockwell
Features a nylon tipped tensioning screw to ensure the solid fit between upper and lower maintains for years to come. 
Functions with nearly all available AR parts kits and uppers.
Flared mag well
Pictogram safe and fire indicators
Chevrons on the front of the mag well and the distinctive Grey Ghost markings tie the Cornerstone to Rifles from Grey Ghost Precision.

0.5 lbs

Due to the change in laws we are no longer able to ship to CT, DC, MD, MA, or NJ  state


  1. Please read the FAQ's page of the web site so you are familiar with payment options, policies, etc.

  2. Federal law requires this product to be transferred through a licensed FFL dealer. Grey Ghost Precision requires a copy of the dealer's FFL for verification. It's the customer's responsibility to notify the dealer of the order. Email or Fax (253) 984-6696

  3. Once we receive the payment and signed copy of the FFL license, we will ship the firearm to your dealer. IT IS YOUR RESPONSIBILITY TO NOTIFY THE FFL DEALER OF YOUR ORDER.


Reviews (11)

corenrstone lower

Written by Lawrence on Jan 21st 2021

Fit and finish are excellent. Bought them in perfect condition, they are ready for hard use.

Very satisfied

Written by Chuan Dang on Jul 2nd 2020

I picked it up a lower from my FFL after reading great reviews, It looks fantastic, I did a side by side comparison with my Mega forged lowers, they are the ssame finish, superb quality, and look. Now I am just waiting for my GGP upper to arrive and everything will be full circle. Extremely pleased.


Written by Joseph John Guccione on Jun 20th 2020

This is the best aftermarket lower available today. The finish is 2nd to none. The included tensioning screw and pre-tapped (4-40) takedown boss are dope. My only fear - price escalation because I will use these exclusively on all my builds. Five Stars

cornerstone lower

Written by Lawrence on Feb 18th 2020

It's worthy of the name. The quality is apparent. Fit and finish are excellent.


Written by Ryan on Jan 11th 2020

These lowers are slick, finish is the best I've personally seen. Fitment to uppers is pretty tight. Engravings are very sharp. Would definitely recommend, especially for the price.

Excellent quality, fit, finish, price

Written by Jaime Halscott on Jan 2nd 2020

I picked four of these up during the Black Friday sale. The price was too good to pass up on. Receivers are perfectly machined and fit with the same uppers I got with no play or wiggle. Almost like these were machined together sets. Finish is not standard milspec anodizing. It is much more like my Wilson Combat and Noveske sets. Highly recommend the for any builds.

Cornerstone lowEr

Written by Kyle on Dec 19th 2019

Very pleased with the fit, finish and quality of the cornerstone upper and lower. I am fairly new to building freedom in my own home and will always seek out GGP before selecting any other AR parts. Everything went together smoothly and I don’t foresee any compatibility issues with aftermarket parts unless the other company has more error in their tolerances. GGP states they are within tighter tolerances and I have not experienced anything less of that. Great product GGP, looking forward to future business with you all.

Solid Lower

Written by Jordan Strepko on Oct 3rd 2019

Lower receiver has excellent fit and finish. Deep lustrous black in color. Tension screw is an added bonus. Would recommend if you are looking for a forged but not "vanilla" lower receiver.


Written by Adam Gray on Aug 16th 2019

Great product far exceeded my expectations

OUTSTANDING. Looks and functions perfectly.

Written by johny 180 on Oct 5th 2018

Holy smokes what a great lower receiver. Used it as the centerpiece of my last build and I could not be happier with the Cornerstone. The lower is solid. It fit well and it functions perfectly. But the cosmetic is my favorite. I love the skull and the finish is by far my favorite in the AR business. Great lower. I'm HAPPY.

High Specs. High quality finish.

Written by DIGGITY10110 on Oct 5th 2018

Beautiful finish on this lower, very strong. Excellent machining. Fits tight with my upper. I would definitely recommend, well worth it. Great job Grey Ghost!

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