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Builders Bundle + (3) 80% Lower Receivers (Billet)


Out of stock

Our Package Includes: 

Modulus Arms Router Jig Extreme™

Modulus Arms invented the first fully universal router jig, and we’ve once again raised the bar. 

The new Modulus Arms Router Jig Extreme™ is the highest quality and the fastest 80 lower jig that will allow you to build the most 80 lowers compared to any other option on the market. Don’t just take our word for it, try for yourself risk-free with our 100% Satisfaction or Money-Back *Guarantee. If you don't love our jig, we will give you a full refund!

The Router Jig Extreme™ comes in one fully universal model that fits all AR-15, DPMS style .308 and AR-9 lowers. No need to buy any extra add-on parts for .308 compatibility. The standard model is fully universal right out of the box. 


  • The fastest 80% Lower jig on the market, capable of finishing an AR-15 80% lower in a record setting sub 45 minute time.
  • Switch between AR-15, AR-9, AR-45 or .308 lowers in seconds.
  • All wear surfaces are made with hardened steel.
  • Our router attachment plate uses a proprietary one piece solid guide pin system to trace fire control group pocket profile guides, ensuring the end mill never touches the jig. This eliminates wear - extending the life of your 80 lower Router Jig Extreme™.
  • The Router Jig Extreme™ utilizes a heat fit (a.k.a. shrink-fit) end mill holder which provides increased rigidity over a standard length carbide end mill.
  • 1.5 in thick no-touch side plates keep your drill bit stable when drilling with a hand drill.
  • Only 1 hole needs to be drilled before milling.
  • Patented integrated depth gauges tell you how deep to mill and eliminate the need for any measuring.
  • Patented integrated vacuum attachment allows you to attach a standard vacuum hose, greatly reducing the mess created by chips.
  • Easy to follow illustrated instruction booklet included. 

Confirm SpeedMill Type

We strongly recommend all customers to only use our proprietary end mill, the Modulus Arms SpeedMill™ with our 80 lower jig. 

Please see the chart below for which routers we recommend to use with our corresponding SpeedMill™ versions (there are 4). You can also pick up a Tool Kit if you want spare tools.

If your router is not on any of the lists, then it is not compatible with our products and we do not recommend using it to complete an 80 lower with Router Jig Extreme™. Please note that all routers that use V4 will need the Large Router Platema-routerchart-website-01.jpg

*Satisfaction Guarantee

Our products are protected by multiple issued and pending US Patents.

It’s possible that some, very rare and oddly shaped non-milspec AR designs will not fit this jig. In the unlikely event that your 80 lower doesn’t fit you may return the jig for a full refund or consider buying one of our 80% lower receivers instead!

Shipping Restrictions

We cannot ship this product to any states or major cities that have passed laws restricting these items such as New Jersey, New York, Hawaii, Connecticut, Rhode Island, Washington D.C., Maryland, Illinois, California, Washington, Allenspark Colorado , Coal Creek Canyon Colorado , Eldora Colorado , Eldorado Springs Colorado , Gold Hill Colorado , Gunbarrel Colorado , Hygiene Colorado , and Niwot Colorado, and Denver Colorado.  Laws change often, be sure to check what your State Laws and Local Ordinances are. 

caution-icon.png The Router Jig Extreme SpeedMill is required for use with the Modulus Arms Router Jig Extreme™ and is not included. Previous generation Modulus Arms end mills will not work with this jig for your 80 lower build. caution-icon.png