Universal 80 Lower Jig - RJ556U for Mil-spec AR-15/AR9 80% Lower Receivers by Polymer80

This jig is compatible with our Forged 80% Lowers. Our Premium Fire/Safe Marked Billet 80% Lowers are not compatible with this 80% lower jig. Other manufacturer's billet 80% lowers may compatible with this 80% lower jig, provided their lower receiver design adheres to mil-spec specifications.

Most 80% jigs are made of precisely-machined alloys, made rugged enough to cut and drill lower after lower. If you’re the once-and-done builder (or you’re working on a tight budget), you’re probably looking for something simpler. Maybe you just want to try out gunsmithing at home and don’t want a big sunk cost. We get it. That’s why we partnered up with our friends at Polymer80 to offer you a new disposable, universal AR-15/AR9 80 lower jig!

The RJ556U jig is made from reinforced polymer and ships with the necessary drill bits and end mill bit to cut and drill any mil-spec AR-15 or AR9 80% lower receiver. This jig’s tough nylon composite allows it to reliably machine polymer and forged or billet aluminum receiver blanks - up to three with the original tooling. All for a super-low price.

The RJ556U Jig Includes:

• (1) Left and Right Side Plate
• (3) Trigger Template Guides
• (1) 9mm HSS End Mill
• (1) 5/16 Drill Bit
• (1) ⅜ Drill Bit
• (1) 5/32 Drill Bit

Cutting and Drilling with The Jig

The RJ556U Jig doesn’t require an expensive mill to operate. All that’s required to use the jig is a standard drill press and some basic measuring devices:

• Vise For Drill Press - 6” jaws
• Drill Press -1850-2250 RPM
• Digital Calipers
• Dremel Bit #9904
• Bubble Level
• Round Machinists File
• Non-marring Vice Jaws
• Lower Receiver Vice Block
• Upper Receiver Vice Block 

Learn how to cut and drill your receiver blank by downloading Polymer80’s written instructions here.