cc-settings-icon BUILD AT HOME
80% Arms sells AR-15 and .308 80% Lower Receivers, 80% Lower Jigs and other accessories which allow you to legally build a firearm at home in most states.
We utilize state of the art 5-axis CNC machines to mill all our .308 and AR-15 80 percent lower receivers to incredibly precise tolerances using premium billet aluminum.
We also offer our patented AR-15 and .308 Easy Jigs which is the first 80% lower jig that makes it ridiculously easy for a non-machinist to finish their 80% lower in under 1 hour with no drill press required.
Products manufactured by 80% Arms carry a lifetime warranty against manufacturing defects. We will promptly replace or repair any product that we determine to be defective.

GST-9: Infinity Jig w/ Tool Kit & Slide Rails

$199.99 - $349.99
Rail Pack Options - Choose One
Calculated at Checkout
Norton Shopping Guarantee

Introducing the 80% Arms GST-9 Infinity Jig. This is the only 80% pistol frame jig on the market that will outlast the ATF. The GST-9 Infinity Jig is sleek, durable and reusable. Every detail that went into this product is meant to ensure high quality completion of the GST-9 pistol frame again and again.

We have a history of leading the market with innovative and high-quality products and the new Infinity Jig is no exception. With the advent of the Easy Jig® and GST-9 Jig, we have set the standard for easy, accurate, and durable jigs for home-building enthusiasts. See How to Use the GST-9 Infinity Jig video on Odysee here!


  • Compact — The sleek profile makes the Infinity Jig easier to secure when drilling into your GST-9 Frame.
  • Premium Quality — Constructed from 6061 high-end billet aluminum, ensuring a long-lasting and extremely durable jig.
  • Backwards Compatible — Fully accommodates both the GST-9 MOD 1 and GST-9 V1 frames, providing flexible use for both old and new customers.
  • Easy to Assemble — With only three simple parts and two screws, assembling your pistol frame jig is effortless.
  • Unlimited Reusability — Heat treated hardened steel bushings maximize durability to ensure consistent holes in your frame throughout the life of the jig.
  • Black Nitride Rails — As an extra long lasting surface layer, the black nitriding will help your rails last even longer with enhanced ability to resist abrasion and corrosion. (Each set of rails comes with the appropriate amount of frame pin sets needed)
  • Extremely Hand Drill Friendly — While you certainly can use a drill press, there's really no need!

Our CNC precision cut rails are made from hardened steel and we are offering them in bundled packs to meet your building needs. These rails are designed for a frustration-free drop-in fit, requiring no additional grinding, sanding, or lapping to install and align. The impact of our industry-leading quality cannot be overstated and will be appreciably noticed by first time and experienced builders alike.

Items in the Infinity Jig:

  • Infinity Jig 
  • Drill Bits - 3MM & 4MM [$5 Value!]
  • Solid Carbide Cutting tool [$10 Value]
  • Jig Screws 
  • CNC Front Rail [$50 Value!]
  • Split Rear Rail Set [$15 Value!]
  • Front/Rear Pins
  • Frame Grip Pins

Now available in packs of 3, 5, and 10! Please note that there are NO discounts available for purchasing a 3-pack of rails. However, if you choose to purchase a 5-pack, each GST-9 MOD1 Frame will be discounted at 10%. And for even greater savings, our 10-pack of rails offers a 20% discount on each GST-9 MOD1 Frame purchase. Discount will automatically apply at checkout.

We also offer single pack rails here, if you don't need any of the pack rails. 

Do you have more questions? Here are some helpful FAQ that has additional information that may answer your questions, if not feel free to reach out directly to our Customer Service by clicking our Chat Bubble located in the bottom right corner of your screen

See the PDF view of the instruction manual here. Or, check out our blog on how to assemble & use the Infinity Jig.

*The GST-9 Infinity Pistol Jig will work on our GST-9 Frames only (which are legally protected by the injunction issued to us by a federal court).

Due to ATF regulations, the jig and GST-9 frame must be added to your cart as two separate items. Each jig includes the amount of GST-9 frame rails you choose to buy in the selectable options. Please note that the frame rails are ONLY included with the purchase of a jig, not with the purchase of 80% lower pistol frames themselves.

Shipping Restrictions: This item is restricted from shipping to California, Connecticut, New Jersey, New York, Washington D.C, Washington, Hawaii, Oakland City, Unincorporated Boulder County Colorado (Allenspark, Coal Creek Canyon, Eldora, Eldorado Springs, Gold Hill, Gunbarrel, Hygiene, and Niwot), City of Denver Colorado, City of Philadelphia Pennsylvania, Maryland, Illinois, and Rhode Island