Lockestone Industries 80% Lower Receivers


Guns & Tactics takes a hard look at the Lockstone Industries 80% lower receiver with Jody Lewis.

I first started seeing 80% AR-15 lowers hit the market in 2008 and by 2012 the 80% market was gaining serious ground due to price drops and a plethora of supply. All of that changed December 2012 when the horrific Sandy Hook massacre took place and the entire country was in turmoil regarding gun laws. That scare created more demand than supply could keep up with and so gun buyers were forced to look at 80% solutions.

Things are starting to creep back to normal and 80% is becoming more and more available. We have entered into that phase where companies are stepping up their game and in order to stay ahead they must stay innovative.

Lockestone is one of those companies. Not only are they making a unique Billet 80% lower, they also have created a universal JIG to work with it. This is important because the majority of jigs on the market are designed to work with mil-spec forged lowers only. Lockestone’s JIG will work with just about every lower out there.

With the patent pending innovation Lockestone has created, it is definitely worth having a hard look at, so I decided to try it out.

80% Lower

Lockestone sent us one Billet lower, which was anodized burnt orange. If that is not your thing, it is available in several colors from black to burnt bronze.

The first thing that came to my mind was why would you anodize a lower before it was machined, wouldn’t the machining processes render the finish useless? To my surprise, you would have a hard time knowing the entire lower had been machined after anodizing. Once it was built and put together with an upper, it is a non-issue.

LockeStone’s 80% Lower Receiver starts from U.S. aerospace grade 7075-T651 aluminum billet stock and is fully machined in the U.S.A. to MIL-SPEC tolerances. The operations left to be completed are the fire control group pocket, trigger pin-hole, hammer pin-hole, trigger slot and the safety selector hole.

Key Features
  • CNC machined 7075-T6 aerospace aluminum billet stock
  • Structurally designed for added strength
  • Bull-nosed magazine well for enhanced ergonomic comfort
  • Integrated trigger guard for gloved use and added strength
  • Enhanced tolerances for a tighter mechanical fit
  • Serrated trigger finger index point
  • Anti-glare Bead Blast tactical finish
  • Mil-Spec hard coat anodized
  • 100% MADE IN THE U.S.A.
80% Universal JIG

In addition to the lower, we received the universal AR-15 JIG, which features a reversible single-piece design. It is constructed of thick, rigid 11-gage steel; this jig is durable enough for machining multiple lowers when used properly and includes all of the guides to finish the machining steps required to complete an AR-15 lower.

The universal 80% JIG is a one-piece jig with the drill patterns built in to reduce milling time. That means instead of hitting the ground running with an end-mill and taking your time milling out the pocket at a slow pace, the drill guide allows you to pre-drill a series of holes and then bore those holes to reduce milling time. In essence this is a faster process that results in less wear on your end-mill.

Machine Bit Set

For those that do not own the necessary bits and pieces, lockestone offers a complete bit set with all of the necessary cutting tools to finish an AR-15 80% lower receiver.

The bit set includes:

  • 5/32 inch Drill for trigger group
  • 3/8 inch Drill for trigger group
  • 3/16 inch Drill for pre-mill hole pattern
  • 5/16 inch Piloted Bore for pocket pre-mill holes
  • 5/16 inch Short Flute End Mill with Full Round Shank for pocket and trigger
Machine Time

Setting up the lower in the jig is pretty straight forward if you follow the printed directions and Lockstone has created a handy tutorial video to aid the first time machinist in finishing their 80% lower.

The most important thing to remember is to take your time, check your measurements and steps twice if not three times. It does not take much to make an error if you are not paying attention, so go SLOW!

I should note this can be done on a home type drill dress if you have a decent mill-drill table vice. I found one at Harbor Freight Tools pretty cheap. This is not the best option but if you are only doing one, this is the route I would go.

For our lower, we used a Bridgeport Mill. Regardless, one of the most important things to make sure of is that your table is level and your x and y axis is straight. You can accomplish this with a travel indicator; again you can find them pretty inexpensive at Harbor Freight.

I generally like higher-end gear, such as Mitutoyo or Starrett for precision, but it is over-kill if you are doing just one lower.

A first time user can expect it to take 2-4 hours to finish their lower on a mill and double that on a mill-drill, so don’t be surprised if you spend all day on it. Generally after you have had more time doing it, you can cut that in half. Setup takes the longest and the cutting is pretty quick.

Other items that can save you time:

I have found that hand fitting is usually needed and a good set of machinist files is a plus.

We were very happy with the quality of all the parts, the instructions, customer support when we had questions and overall had a great experience. The lower went together without issue and we took it to the range to put some rounds downrange. Our test gun experienced no issues and functioned perfectly.


The only issue we ran into during the machining process was keeping the precision pins in place. These are the pins that hold the lower in place while machining. Our pins kept falling out and at times the pins were in to far so our mill bit hit them. This could be improved but is really more of a frustration that can be overcome with patients.

You can get more information http://www.lockestone.com and check out there AR-10 offerings while there, too.


Comments are closed.