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80% L❂WERS

Building An 80% Lower

While there are federal and state regulations governing the manufacturing and distribution of firearms, the BATF does make one slight exception in regards to building an 80% lower. Within most states it is legal to possess and manufacturer a firearm from an 80% lower.

The BATF does not consider an 80% lower to be a firearm and permits the completion and operation of the lower for personal use only.

According to the BATF: Individuals manufacturing sporting-type firearms for their own use need not hold Federal Firearms Licenses (FFLs). However, we suggest that the manufacturer at least identify the firearm with a serial number as a safeguard in the event that the firearm is lost or stolen. Also, the firearm should be identified as required in 27 CFR478.92 if it is sold or otherwise lawfully transferred in the future.

Building An 80% Lower

Building an 80% lower can be done quickly and economically. ( offers multiple choices of 80% jigs that will make this process much more efficient.) If you possess any sort of handyman skills, it should be a simple process. By using a drill press, end mills and bits you should have your 80% lower done in no time. Depending upon the jig you use, finishing an 80% lower should take 1-3 hours.

For most people, building an 80% lower comes down to the challenge associated with a ‘do-it-yourself’ project. It’s the sense of accomplishment and pride of knowing you had a hand in finishing your firearm that makes it worth the extra time and effort.

Take Your Time

One of the most important elements in building an 80% lower is to take your time. There is no trophy to win and no one’s keeping track of how long it takes. Calculate each measurement correctly to insure your bits and end mills are set to their proper depth before you start your project.

By paying close attention and carefully positioning each movement will insure your fire control group will function properly. When it comes to milling of the receiver pocket a few thousandths in depth will not be detrimental to the overall function of the AR. Simply taking extra precautions during the milling process will result in a reliable firearm.

Once the lower is completed test-fit with the upper receiver to make certain the takedown-pin holes align properly. You will also want to insure the hammer, trigger and selector switch fit and function properly.

Installing a Lower Parts Kit

With the 80% lower milled, finished and fitting the upper correctly, it is time to install the lower parts kit. This kit will include all the pieces necessary to make the lower function as an operable firearm.

As you install the lower parts kit, be sure that each pin fits correctly and do not attempt to apply unnecessary force in any way. Although a light tap may be needed at some point, refrain from forcing any parts to the point where there could be breakage.

Now that your lower parts kit is installed and your upper fits correctly, it is time to have some fun. Remember safety first and always support the second amendment. is proud to offer quality service to its customers. If you have questions or comments regarding the building of an 80% lower, please feel free to contact us.

DISCLAIMER: If you are new to the world of DIY gun building, you likely have a lot of questions and rightfully so. It’s an area that has a lot of questions that, without the correct answers, could have some serious implications. At 80 Lowers, we are by no means providing this content on our website to serve as legal advice or legal counsel. We encourage each and every builder to perform their own research around their respective State laws as well as educating themselves on the Federal laws. When performing your own research, please be sure that you are getting your information from a reliable source.


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