You decided to build an AR-15 (awesome!). You’ve picked out an 80% lower and a jig, and now you’re trying to figure out what else you’ll need to actually finish the job. You’ve come to the right place! In this article, we’re breaking down the seven tools you need to complete your 80 lower like a boss. We’ll talk about why each tool is important, and we’ll recommend the perfect option for that tool’s category based on our own experience.
Some builders use a drill press to mill their 80 lowers, but many of us simply don’t have access to one. Fortunately, 80 lowers were designed to be completed without a drill press – only a hand drill and handheld router. There are many routers available that’ll get the job done, but there’s one in particular that every builder loves: The Porter Cable 450.
The Porter Cable 450 is the handheld router that many jigs are designed to work with, and hundreds of AR builders have chosen it for their 80 lowers. There are plenty of features packed into the Porter Cable 450 that makes it perfect for machining aluminum:
- Features a soft-starting 1.25-HP motor
- Electronic feedback maintains motor speed through each cut
- Bit depth adjustment ring provides small, 1/64″ adjustments
- Depth ring and clamp combines to ensure motor remains locked
- Large 4″ sub-base accepts universal template and 80 lower jig guides
- Extended 8-slot, 1/4″ collet provides more grip on router bit shank
Basically, the Porter Cable 450 is the perfect size for an 80 lower, it packs plenty of torque to cut through metal, and it provides precise adjustments (obviously necessary for machining a precision firearm). The 450’s setup also ensures your bits are perfectly seated and aligned, preventing and mistakes while machining.
Drill Press or Hand Drill
You’re going to need a drill of some sort to drill the pilot hole(s) in your 80 lower. A drill press is the optimal choice, but this can be done with a hand drill. No matter which way you drill your lower, ensure that your jig is on a level surface and is properly seated.
Most jigs’ guide plates use reinforced fittings and self-aligning guide holes, allowing for safe and accurate use of an electric power drill. We recommend using a corded power drill. Cordless drills exert different torque ratings and speeds as their batteries discharge, especially when drilling through metal. This could result in rough or poorly drilled holes in your 80 lower.
Bench/Drill Press Vise
Investing in a bench vise for this project is a no-brainer. Once you’ve seated your lower in your jig, you’re going to need a stable platform that prevents your setup from moving around while you cut and drill. While most 80 lower jigs are heavy, they can still be shifted and knocked loose while you’re working. If this happens, the chances of making a mistake and ruining your lower are high. We picked this particular vise for its low price, small size, and heavy-duty cast iron construction.
For the purpose of gunsmithing, a vise that opens at least 4″ (like our pick) is recommended. You’ll also want some clamps or screws to hold the vise down to the plate of your drill press or table top. Speaking of…
AR-15 Roll Pin Punches
A jig, router, and vise will get you to the point of completing your 80 lower. Once finished, you get to install your lower parts kit! Unless you’ve purchased a Premium Lower (which has threaded fittings instead of roll pin fittings), you’ll need a roll pin punch set. Trust us, you do not want to attempt installing roll pins with a punch set like this.
Attempting to use a screwdriver, nail, or other improved punch will likely result in your roll pin flaring out and becoming un-usable. Worse, you could scratch the finish on your 80 lower before it’s even finished. These AR-15 roll pins are designed for lower parts kits and they feature specially tapered and rolled ends for each roll pin you must install.
Brass Gunsmith Hammer
So, how are you going to drive in those roll pins and punches? With a big ole’ mallet? No, lest you want to trash your lower with a wayward strike. Instead, you’ll need a decent gunsmith hammer with a rubber or brass head. There are plenty of options out there, but we chose this one for its price and perfect size. This hammer uses a 3-ounce, 5/8″-wide head, just the right size and weight for hitting those punches precisely.
A 9-1/8″ handle gives just enough leverage for driving the pins in, without offering too much “swing-and-a-miss”. This hammer sports a brass head and wood handle, reducing the risk of damaging your lower’s finish or aluminum. We found brass works better than rubber – it bounces less and drives those tight pins in more readily.
If you’re building an AR-15 using a pre-built upper receiver (or pre-built lower assembly), then an Armorer’s Wrench is convenient. If you’re building your AR using an 80% lower, the Armorer’s Wrench is most definitely required. You’ll need one to properly install your upper’s barrel nut. You’ll also need the wrench to install your buffer tube’s castle nut. And if you ever want to swap out your upper’s handguard or your barrel’s muzzle device – you guessed it, Armorer’s Wrench.
We opted for a simple, affordable, forged unit that’s made in America. We picked this particular wrench because all the fittings and tool-ends are on one side. This allows for a longer handle which provides better torque and grip. Some Armorer’s Wrenches are double-ended, splitting the fittings between each end, and these can be difficult to grip.
You don’t want to be half-way through machining your 80% lower when a drill bit breaks, stopping you in your tracks. You can’t remove a lower from your jig once you start work, so it really pays to invest in just a few extra drill bits and end mill bits. Most jigs recommend having one spare end mill bit for every two to three lowers you complete, and we agree. We also don’t recommend using any old end mill bit you can buy at the local hardware store.
The bits we sell (and the bits included with any 80 lower jig) were specifically designed for gunsmithing. Using sub-par bits may result in a poorly finished lower – one that can’t even have a lower parts kit installed reliably. Replacement drill bits and end mill bits can be found here.