Quality, integrity, and value. These words are important to us when we consider making any kind of purchase or investment. In an AR, the most important piece is the lower receiver, and this piece alone constitutes a firearm in the eyes of the law.

There are a few companies selling lower receivers, these are supplied by fewer manufacturers, and these in turn are supplied by one or two sources of raw receiver blanks.

This first step in the manufacturing process is a key part of the quality of the finished receiver. All receivers are not the same, and sometimes not as they appear.

Casting
The "casting" of a receiver is the process of getting molten aluminum inside a mold. There are different ways this can be accomplished, and although it sounds simple, this can truly be an art when done properly.

Gravity Casting - Gravity casting is the most basic process of pouring molten aluminum into a mold; this uses gravity to fill the mold. It features a very reasonable production cost and is a good method for casting designs when reducing weight is not a concern. Since the process relies on gravity to fill the mold, the aluminum is not as densely packed in the mold as some other casting processes.

Low Pressure Casting - Low pressure casting uses a positive pressure to move the molten material into the mold quicker and achieve a finished product that has improved mechanical properties (more dense) over a gravity cast piece. Low pressure casting carries a slightly higher production cost over gravity casting. Higher pressure casting can result in a lighter and stronger piece, but there is a higher cost associated with it.