
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.
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 Plate.
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!
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.
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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. | ![]() |