We have plenty of rifle receivers for sale here in our dedicated Rifle Receiver Category.  Including complete AR-15 lower rifle kits, 80% stripped lower receivers (not considered a gun by the ATF and does not have to go through a dealer), bolt action rifle receivers, other assault rifle lower receivers, 308 rifle lower receivers, and many more.  

The lower receiver for a rifle (as opposed to the upper receiver) is usually the serialized component of the firearm that is tracked by the ATF as a firearm.  A stripped lower comes without the attaching parts, while a full receiver comes with most or all parts needed to assemble a gun.  Almost all receivers must go through your local dealer for pickup, like a gun, unless otherwise notated.  If you have any questions, please let us know!