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JMT 'Carbon 50' AR-15 80% Gen 2 Polymer Lower with Jig - Black

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Lighter is better, right? Damn right it is! Nobody wants to carry around more weight than they have to. Ask any good shooter, they'll tell you, "Sure, you might be able to carry a bunch of weight, but why do it if you don't have to?"

So, James Madison Tactical took one of the lightest AR receivers -- polymer -- and made it even lighter by fabricating the first carbon fiber/polymer hybrid 80% lower. It's super lightweight, yet stronger and more durable than other AR-type polymer 80% lowers. It comes with its own jig too, so all you need is a drill press! The finished receiver will shave those precious ounces off the weight of your workhorse too, so you can have a little more comfort during a long day of shooting.

Carbon 50 Polymer 80% Lower Features:

  • Weighs just 4.4 ounces when finished
  • 20% weight reduction over standard AR lowers
  • Stiffer and stronger than many other polymer lowers
  • Mil-spec dimensions make the Carbon 50 fit with all other types of mil-spec parts

Why a Polymer AR-15 80% Lower?

Polymer 80% lowers have been well-tested and proven among the AR-15 and 80% lower community. These ultralight lowers afford the same ruggedness as any aluminum lower, yet its construction also affords many unique benefits.

If you’re nervous about machining an 80% lower, this polymer lower will be the perfect way to ease into the practice. Polymer is incredibly simple to drill and mill, and the material is forgiving.

Manufacturer instructions can be found here.

WARNING: Handling firearms parts and accessories can expose you to lead and other petroleum products known to the State of California to cause cancer and reproductive harm. For more information go to:

Shipping Restrictions

Shipping of various parts and/or accessories are prohibited to states and locales (ie New Jersey, California, New York, etc…) with restrictions against certain parts and/or accessories or "assault weapons" (i.e. states with high-capacity magazine restrictions, manufacturing of semi-automatic weapons, etc..). It is your responsibility to be aware of your local firearms laws before purchasing from our website or machining a firearm. We try our best to keep our shipping page current, but laws change daily. only ships within the United States. Federal legislation dictates we cannot ship our products internationally.

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James Madison Tactical

We are a national retailer of individual components and not all products depicted on this website are legal in every state. Shipping of various products found on this website are prohibited to some states (such as California, Connecticut, District of Columbia, Hawaii, New Jersey, New York, Rhode Island, and Washington). The information, pictures, text or products presented on this website are not a representation by us, and should not be understood by you, that any product or completed firearm is legal to assemble or own in your state of residence. We encourage each and every builder to perform their own research about the state and federal laws that apply to them. It is your responsibility to understand the law and we encourage you to consult with an attorney or your local ATF representative.