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Golden Park

New member
I am new to this forum community. I read a lot of threads here and just here, pretty much. As a member of another forum community, I often hear the terms lower, upper etc tossed around in the thread. I just want to get a clear understanding as to what an AR 15 lower is? How important is the lower and where does it actually...go on the AR 15?


New member
The lower refers to the lower receiver of the rifle. When we are talking about the lower receiver of the AR-15 in particular, the receiver comes into parts that both function quite differently. The lower receiver holds the fire control group, the buffer system, and trigger group essentially. The upper receiver contains the bolt carrier group , barrel assembly, forward assist and charging handle. So as you can see, the two have different functions, but in reality, the platform itself is very easy to handle, which is why it is great for first timers. ARs are great introduction firearms because of its easy-to-use platform and its cheap caliber.

Frankie J

New member
one issue not addressed is that the lower receiver is called the lower receiver for a reason, it has a counter part called the upper receiver. this has now had the courts reversing ATF rules (not laws) that the lower is only half of the legal definition of a receiver. so the lower and upper are the receiver as a whole. to be a receiver under the law it must contain several critical components. the lower holds 3 of those. so in technical terms the 80% lower is in fact only 50% of the receiver. the lower as it refers to the AR/DPMS style firearm is the core of the gun, the upper attaches to it, as well as the stock and grip. the upper which sits on top or the upper part of the gun contains the barrel, bolt (firing pin. ejector, etc...) the charging handle and may allow for an optic to be mounted to it via a rail system running along its spin or top side length of the rifle (pistol if you make a shorter system)