View Full Version : Uppers, lowers-I need help

AntiBubba 2.1
12-11-2005, 8:26 AM
I've never paid much attention to the AR15, since my tastes run to Russki surplus, but with the non-list .223 threads and the possibility of building my own EBR, I've started reading. What still confuses me is the upper/lower receiver difference. I know that the lower is considered legally to be the "firearm" but I don't know why. Would someone be so kind as to explain the difference, and what each half does? Thanks

12-11-2005, 9:02 AM
It is because the BATF says it is. The lower is were the trigger group and the magazine feed resides. It is also where you attach the stock and pistol grip. The upper receiver is where you will install the bolt carrier group, the charging handle, sights if it's not already integral to the receiver, the barrel and the handguards. That would be your basic AR. The upper receiver attaches to the lower receiver by two pins inserted at the front and the rear of the lower receiver. Perhaps this Arfcom AR15 Diagram (http://www.ar15.com/content/guides/parts/) will help.