The AR-15 is the most common rifle in the US and 80% lower receivers (with a jig) are the most convenient way to get into legally making your own AR15.
An 80% lower is the closest you can get to a completed firearm without it legally counting as a completed firearm. This means they can be directly shipped to you without involving an FFL.
This practice is currently completely legal, but with the ever shifting legal landscape and the social stigma attached to 80% lowers, many people have questions about them.
So we’re going to go over everything you need to know about 80% lowers and AR15 80% jigs.
What is an AR15 / 80% Lower Jig?
Jigs are tools used to complete an 80% lower. Since AR15 80% lowers are not finished firearms, they need to be milled out the final “20%” in order to accept things like the trigger group and other parts required to function. This is achieved the easiest with a jig.
Jigs can be made of polymer or steel that help line up the areas that need to be milled/drilled out by you. They allow you to easily drill out the various pin locations and the internal areas of the lower receiver without any guesswork. They can regulate how deeply you drill and the size of bit you use so you won’t mess up your 80% lower.
Best AR15 / 80% Lower Jig
There are many options available on the market for 80% lower jigs and it can be confusing to choose which is best for you.
This comes down to a few parameters:
- How durable is the jig is
- How easy the jig is to use
- How expensive the jig is
With these in mind let’s look at some of the best options available.
Easy Jig Gen 3 80% Arms
This Easy Jig Gen 3 is expensive but is the easiest and fastest AR15 Jig we tried.
The patented Easy Jig® Gen 3 Multiplatform™, a fully universal, 80% lower jig capable of finishing AR-15, AR-9, AR-45, and DPMS.
This jig set is compatible with every AR-15 variant and is compatible with DPMS Gen 1 .308, AR-9, and AR-45 lowers. This means you can mill out standard 5.56 lowers, pistol caliber versions, and the more popular .308 models with a single jig.
The jig features allowances for most tolerances in production, does not need any special adapters for conversions, and does not need to be disassembled to remove the lower. It also allows for a lower to be completed in under 30 minutes, making it the fastest option on the market.
Everything comes pre-measured and gauged so all you need is a hand drill and a handheld router in order to complete your project. The jig is also very durable with a hardened steel construction and hardened steel bushings.
The only drawback is the price. This is one of the more expensive options, but offers the most benefits in terms of speed and ease of use. If you plan on building out a lot of rifles, this jig is worth every penny.
Pros:
- Easy to use
- Works on all AR-15 variants
- DPMS Gen 1 .308 compatible
- AR9/AR-45 compatible
- Steel construction
Cons:
- Cost
Solid runner up to the Easy Jig while saving a few bucks.
The Router Jig PRO Multiplatform allows you to finish all known AR-15, AR-9, AR-45,.308 and AR-10 80% lowers, all in one easy to use machining jig.
This jig is another universal option that can work with polymer, billet, and forged receivers. While most lowers will work with this jig, a special conversion kit is required to work on Cerro Forge Ruger SR-762 lowers. Other than this one exception, your lower will work with this jig.
Extremely durable, this jig set is made of hardened steel and can work with 5D tactical’s ReadyMill™ for the smoothest routing results.
This is another expensive jig option, but it simplifies the entire process. To assemble the jig, you only need to use a total of 14 Phillips screws and you won’t have to take the jig entirely apart to remove your lower.
Pros:
- Integrated depth gauge
- Easy, 3 step process
- Universally compatible (barring Cerro Forge Ruger SR-762)
Cons:
- Another expensive option
Extremely affordable option but you may want to spend the extra $$$ to save yourself from headaches.
The Polymer80 Universal Jig Kit was created for compatibility with mil spec 80% AR15 lower receivers regardless of polymer or metal construction.
If you just want to work on one or two rifles, this polymer jig is worth considering. This jig comes in at a much lower cost than its competitors but is not as durable.
The polymer jig works with polymer and aluminum lowers. A set of guides, bits, and a mill end are included in the kit. It does require more supporting tools than the other options, which can make it more expensive for some individuals.
Since it is made out of long-fiber nylon, it has a usage life. This is roughly three uses before the jig is worn out.
Pros:
- Low cost
- Includes some necessary parts
- Compatible with polymer and aluminum lowers
Cons:
- Not as durable
- 3 uses maximum
Works great but only on AR15 mil-spec lower receivers.
The fast, accurate, bombproof 80% Lower Jig from Elite Builder now ships with equally high-quality drill bits and end mill bits.
A more economical option, this steel jig allows you to have some of the benefits of a more expensive jig but without having to spend a significant amount of money. But you will have to have more tools in order to get the job done as a result.
It is compatible with AR-15 and AR9 lowers but these have to be in a standard/mil-spec configuration. It is specifically designed to be used with a drill press, which means that a router or laminate trimmer is not going to work with this design.
Pros:
- Drill bits included
- Durable
- Fits mil-spec lowers
- Self-aligning
Cons:
- Non-universal
- Requires a drill press for best results
- Not compatible with a laminate trimmer or router
Budget friendly option that still works great but will take a bit more time.
Broken Arms AR15 Lower Receiver jig, tooling kit, and a drill press is all you need to turn your 80% receiver into a fully functional 100% AR15 receiver.
This is a great option if you are going to work with forged lowers. This kit is CNC machined with hardened drill bushings, integrated depth chart, and individually engraved parts. This means you’ll use the right bit with the right hole at the right depth.
While this will take out the guesswork, it is not a standalone option. You will need additional tools and it is not a quick change system. This is fine if you like to take your time with things, but building a rifle takes long enough as it is.
This option falls in the middle of durability and cost. It is not as expensive as some jigs and it can be used many times, however it is not the fastest jig to work with.
Pros:
- Affordable
- Durable
- Multi-use
Cons:
- Requires drill press
- Additional tooling not included in base jig set
- Slow to use
FAQs
Wrap Up
There are many jigs available on the modern market that will allow you to easily complete your 80% lower. Each provides a different benefit, whether that is ease of use, long term durability, or a lower entry price.
Which one is best for you is determined by how much you want to spend, how many lowers you want to work on, and what tooling you have on hand. This list are some of the best options to choose from for the least hassle.
You are now ready to work on your personal rifle with a lower receiver you milled yourself. If you are looking for an easier first time build check out our in-stock Polymer 80 pistol frames.
If you think there’s a jig that should be on this list or you found this article helpful, leave a comment below and check out our other articles.
