Builder’s Guide to 80% Jigs: Drill Press vs. Router
What is an 80% lower jig?
An 80% lower jig is a fixture that holds an AR-pattern 80% lower steady and lines up your tools, so your build comes out accurate and repeatable. A good jig takes the guesswork out of alignment and depth, which is why it matters more than almost any other tool in the build.
Jigs come in two basic types: drill press jigs and router jigs. This guide explains the difference, why every jig Gun Builders Depot carries is a drill press jig, and how to pick the right one for your platform.
Drill press jigs vs. router jigs
Drill press jigs
A drill press jig is built to be used with a bench-top drill press or a milling machine. The jig clamps the lower, and its plates guide the tooling to the right locations. Because the machine controls the cutting tool, drill press jigs are the easier choice for first-time builders, and with no tool sliding across the plates, they hold up well over multiple builds.
Typical parts of a drill press jig:
- Side plates that clamp the lower and locate the pin holes
- Top plates that guide the tooling
- Hardware that holds the assembly rigid
- Tooling, included in some kits and sold separately for others
Router jigs
A router jig is used with a handheld palm (trim) router. The router sits on a base plate on top of the jig and is guided by hand. Router jigs were common when 80% lowers first came out, but they need extra plates, still require a drill press for the pin holes, and depend more on the builder’s control of the router. Gun Builders Depot doesn’t currently carry router jigs.
Side-by-side comparison
| Drill press jig | Router jig | |
|---|---|---|
| Machine you need | Drill press (or milling machine) | Palm/trim router, plus a drill press for the pin holes |
| Learning curve | Beginner-friendly; the machine controls the cut | Steeper; you guide the router by hand |
| Finish | Clean; may need light cleanup | Smooth when done carefully |
| Wear on the jig | Low; no tool rides on the plates | Higher; the router base slides on the jig |
| Up-front cost | Lower if you already own a drill press | Router jigs need extra plates and a router |
| Dust and noise | Less | More aluminum chips and noise |
Bottom line: if you own or can get a drill press, a drill press jig is the simpler, more forgiving and longer-lasting choice. That’s why it’s the only type we stock.
The drill press jigs we carry
- Elite Builder 80% Lower Jig (AR-15/AR-9): our most popular jig
- Elite Builder 80% Lower Jig (AR-10/.308): the same design sized for AR-10/LR-308 lowers
- The Elite Builder Patriot 80% Lower Jig: one jig for AR-15, AR-9 and AR-10 lowers
- Liberty 80% Lower Jig (AR-15/AR-9): a solid mid-range option
Compare them side by side, including platform fit and price, on our 80 lower jig page.
Tooling
The jig guides the tooling, so the tooling has to match the jig. Use the tooling specified by your jig’s manufacturer; mismatched tooling is the most common cause of a poor fit or a damaged jig. We carry matched kits:
- Elite Builder (for 80% Jig) Tooling: matched to the Elite Builder jigs
- Juggernaut Tactical Tooling: for the Juggernaut Tactical Universal Jig
Not sure which tooling fits your jig? Check the product page or browse jig tooling and parts, or contact us before you order.
How to choose
- What platform are you building? AR-15 and AR-9 lowers share a jig; AR-10/LR-308 lowers need an AR-10 jig or the Patriot. Our 80% jig compatibility guide covers which lowers fit which jig.
- Do you have a drill press? All of our jigs are designed for one.
- Do you want tooling in the same order? A matched tooling kit avoids sizing mistakes.
- How many builds are you planning? The Patriot covers three platforms, and replacement top plates are available for the Elite Builder jigs.
Before you order: shipping restrictions
Some states, cities and counties restrict 80% jigs and jig tooling, and we don’t ship them to those locations. See our jig shipping restrictions for the current list. You’re responsible for following all federal, state and local laws where you live.
Questions about which jig or tooling is right for your build? Shop all 80 lower jigs or reach out; we’re happy to help.
