I, for one, will never understand the fascination with 80-percent firearms. I don’t need an unregistered lower receiver or care if it has a serial number in a database. As my old mentor from the U.S. Marine Corps once told me, “If it’s time to start burying guns, it’s already time to start digging them up.”

But I do support a free market economy, so if that is your bag, good for you. I can understand that there are tinkerers and mechanical wizards that like building firearms from the ground up. This week, I was tasked with building a polymer lower from a mold. In the title we called it “epoxy” because it is a two part solution with a hardening compound. On the website they call it resin, so I’m sure it is similar to epoxy, like a Bakelite kind of material.

Legally, this kit is not unlike the 80% kits. It is legal under federal law to manufacture a firearm for your own use, and it does not ever require a serial number or registration (state laws vary). But unlike the 80% kits, this comes out of the mold as a finished receiver. There is no milling machine or sideways grinding required, and you don’t even have to drill the holes. As you can see from the video, all this receiver needs when it comes from the mold is a little touchup with a dremel. The kits come in 5, 10 and 15 pour versions, starting at $339. I had frustrations with bending the metal insert components, and I noticed on the website that they now are pre-bending them, because I was not alone. If I continue to test this over the summer I will mold a different one with the metal inserts molded in as designed.

Pour Me Another Barkeep

I started this process extremely skeptical. Let the record show that I have nothing against polymer firearms, resin firearms or any other kind of firearms that work and are a good value, but starting with the sketchy instructions, I didn’t have a great feeling about this one. I have yet to see an AR lower made of anything besides aluminum or carbon fiber that lasts.

Ideas are just ideas. One of the first attempts at an off-the-books lower receiver that I witnessed was a 3D-printed model. It proceeded to crack at the buffer tube after roughly 30 rounds — as did the nine prototypes that followed.

There have also been a flood of AR lowers into the market as the firearm market exploded over the last 8 years. I have seen AR lowers, some as cheap as $40, made by real companies in aluminum that were trash due to misaligned holes and/or questionable tolerances. An AR lower isn’t exactly rocket science, but many companies get it wrong. I like my Glock and SIG Sauer polymer pistols, but they don’t make those in a red Solo cup, like I made this one. This product is just another idea, and on my first pass it did work, but we’ll see in time if the finished product is at all resilient and reliable.

On the plus side, an AR-15 lower doesn’t take a lot of stress. Aside from the aforementioned 3D-printed models, I haven’t seen very many damaged beyond use. The exceptions to that rule involved shrapnel and or overpressure that also put the shooter of that rifle out of commission. The Marine Corps and U.S. Army issue units that have taken severe punishment over the years, and in my years of service, I’ve never seen one worn out. Can a lower made of resin, concocted in a red Solo cup stand up to whatever mild abuse it will be expected to endure? I don’t know.

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Impressions Are Molded

The AR mold kit we received is a novel concept. Put the two halves together, stick removable pins in where you need holes, fill full of liquid polymer, and have a cold one while you wait on the paint to dry. It offers the option to make any color you want, and as long as you have lower parts kits and polymer resupply, an endless resource for lowers.

First, let’s talk about the bad. The directions are at best Mickey Mouse. We ended up winging it based on a variety of YouTube user experiences. Given the less-than-explanative directions, I was amazed that our lower didn’t shatter the first time we looked at it funny. Included in our kit was a steel reinforcing segment to install at the buffer tube threads. I assume this is to correct the same weakness as was showcased in the 3D print models. For reasons unknown, this is a part you must bend to fit on your own. After I wasted five of our 15 parts and spent well over an hour cursing the day the inventor was born, I tossed them across the garage and proceeded without them. The original bolt together system failed us, so I supplemented with C-clamps and wood screws. A little survivalist McGuiver helped carry the day. The final product required some fitting with both a Dremel tool and a pocket knife. This was mostly correctly sizing or completing the pin holes.

A Resin Lower is Born

Amazingly, the final product assembled with relative ease and functioned. All the normal AR parts worked, and our parts kit from Mid-South Shooters Supply went together smoothly. I test fired 30 rounds of military surplus and noticed zero cracks or weaknesses.

Lasting Impressions

So, what is the final tally? If you are interested in building your own lowers, this is a win. Despite my skepticism, it did its job. If you are looking for an “Ghost Gun” AR solution, this requires fewer tools and knowledge than other options.

The downside is the time and the cost. I have assembled a few lowers in my day, and they usually take about 30 minutes. On my first mold lower, I spent about six hours just in completing the lower. The kit we received will do 5 lowers, provided you don’t screw up your chemical mixture, at a cost of $339. I’m sure subsequent attempts will not take me as long, because just like installing a new sink, the first time is always a learning experience, but you should be aware going in that this isn’t a quick thing, and you might screw up your first one.

Overall I personally am still not terribly impressed and I don’t see the value. The same week that I was testing this kit I bought a fully assembled lower with buttstock included on close out from Palmetto State Armory for $150. And that is with genuine Magpul furniture included. And besides cost and time, as to durability, only time will tell with these molded lowers. I will keep using one until it breaks or I believe it won’t be smart to let it rattle further, but that is going to take a few weeks, and it hasn’t started rattling yet.

For more information about AR15Mold.com, click https://ar15mold.com.

For more information about lower parts kits from Mid South Shooter Supply, click https://www.midsouthshooterssupply.com/item/00045lowerpartskit/ar15-lower-parts-kit.

To purchase an AR-15 reciever set on GunsAmerica, click https://www.gunsamerica.com/Search.aspx?Keyword=AR-15%20lower.