Completing an AR-15 80% lower receiver is a rewarding project, but success depends heavily on choosing the right tools—especially the jig kit. A jig kit is your guide, ensuring precision and accuracy as you drill and mill your lower receiver. With so many options available, it can be challenging to determine which jig kit is best suited for your needs.
In this article, we’ll explore the key factors to consider when selecting a jig kit, break down the different types available, and offer recommendations to help you make the right choice for your AR-15 80 lower build.
What Is a Jig Kit and Why Is It Important?
A jig kit is a specialized tool designed to hold your 80% lower receiver securely and guide your drill and router as you machine the fire control cavity and drill the necessary holes. It serves as a template, ensuring you remove the right amount of material in the correct locations.
Key Functions of a Jig Kit:
- Precision: Guides your tools for accurate cuts and holes.
- Safety: Keeps the lower receiver stable, reducing the risk of mistakes or injuries.
- Ease of Use: Simplifies the machining process, making it accessible even for beginners.
Factors to Consider When Choosing a Jig Kit
1. Compatibility with Your Lower Receiver
Not all jig kits are universal. Ensure the jig you choose is specifically designed for your AR-15 80% lower receiver.
- Platform-Specific Jigs: Some jigs are tailored for AR-15, AR-10, or AR-9 platforms. Confirm that the jig matches your lower receiver type.
- Material Compatibility: Aluminum and polymer lowers may require different jigs or setups.
2. Material and Durability
Jigs are typically made from one of two materials:
- Aluminum: Durable and long-lasting, aluminum jigs can handle multiple builds without wearing out. They’re ideal for serious builders or those planning to complete multiple lowers.
- Polymer: Lightweight and affordable, polymer jigs are great for first-time builders or those on a budget. However, they may wear out after repeated use.
Recommendation:
If you’re planning to build more than one lower, invest in an aluminum jig for durability and reliability.
3. Ease of Use
Some jig kits are designed with beginners in mind, offering features that simplify the machining process:
- Pre-Drilled Templates: Clearly marked templates reduce the chance of mistakes.
- Tool Compatibility: Look for jigs that work with standard routers or drills you may already own.
- Step-by-Step Instructions: High-quality jigs often include detailed guides or online tutorials.
4. Included Accessories
Many jig kits come with additional tools and accessories to streamline the machining process. Consider kits that include:
- Drill Bits and End Mills: Ensures you have the correct sizes for your lower receiver.
- Depth Guides: Helps you achieve precise cuts without over-milling.
- Replacement Parts: Extra plates or templates can extend the life of the jig.
5. Reusability
If you’re planning to build multiple lowers, choose a jig that can handle repeated use. Aluminum jigs are generally more durable and better suited for multiple builds, while polymer jigs may wear out after a single project.
6. Price and Value
Jig kits range from budget-friendly options to premium setups. While price is an important factor, don’t sacrifice quality for cost. A well-made jig kit ensures better results and fewer headaches during your build.
Types of Jig Kits
1. Router Jigs
Router jigs are among the most popular options for completing AR-15 80 lowers.
- How They Work: Use a compact router to mill out the fire control cavity.
- Advantages: Affordable, beginner-friendly, and compatible with common routers.
- Best For: Builders completing one or two lowers who want an easy-to-use solution.
2. Drill Press Jigs
Drill press jigs are ideal for builders who own a drill press and want precise results.
- How They Work: Guide the drill press to create pilot holes and mill the cavity.
- Advantages: Superior precision and stability compared to hand-held drills or routers.
- Best For: Builders with access to a drill press and experience with machining.
3. Universal Jigs
Universal jigs are designed to work with multiple platforms, such as AR-15, AR-10, and AR-9 lowers.
- Advantages: Versatile and cost-effective for builders working on different platforms.
- Best For: Enthusiasts who plan to build multiple types of firearms.
Recommended Jig Kits
1. 5D Tactical Router Jig Pro
- Material: Durable aluminum.
- Features: Universal design for AR-15, AR-10, and AR-9 lowers.
- Why It’s Great: Beginner-friendly with detailed instructions and a secure fit for lowers.
- Best For: Builders seeking a high-quality, versatile jig.
2. Modulus Arms Heavy-Duty Universal Jig
- Material: High-strength steel and aluminum.
- Features: Includes depth gauges, drill bits, and end mills.
- Why It’s Great: Built to last for multiple builds and platforms.
- Best For: Experienced builders who want a long-lasting jig.
3. Easy Jig Gen 3 by 80 Percent Arms
- Material: Hardened steel plates and aluminum templates.
- Features: Works with common routers and includes comprehensive guides.
- Why It’s Great: Easy to use with excellent customer support.
- Best For: First-time builders who want a reliable, beginner-friendly kit.
Tips for Using Your Jig Kit
1. Read the Instructions Thoroughly
Familiarize yourself with the jig’s setup and operation before starting. Many manufacturers provide online tutorials for additional guidance.
2. Secure the Jig and Lower Receiver
Ensure the jig and lower are tightly secured in a vise to prevent movement during machining.
3. Take Your Time
Precision is key when completing an 80% lower. Work slowly and steadily to avoid mistakes.
4. Use Cutting Fluid
Cutting fluid reduces heat and friction, prolonging the life of your tools and improving results.
5. Clean Frequently
Remove metal shavings and debris regularly to keep your workspace clean and your tools functioning properly.
Avoiding Common Mistakes
Mistake 1: Using the Wrong Jig
Ensure the jig matches your lower receiver and the tools you plan to use.
Mistake 2: Skipping Pilot Holes
Drill precise pilot holes before milling to guide your router or drill press.
Mistake 3: Over-Milling
Monitor your depth closely to avoid removing too much material.
Final Thoughts
Choosing the right jig kit is one of the most important steps in completing an AR-15 80% lower receiver. By considering factors like compatibility, durability, and ease of use, you can select a jig that fits your needs and ensures a successful build.
Ready to start your project? Check out Thunder Tactical for premium 80% lowers, jig kits, and all the tools you need for your AR-15 build. With the right setup, you’ll be on your way to creating a reliable, custom firearm in no time!