Originally Posted by
CrazyFingers
To make that an accurate comparison, the G19 frame would have to be a dimensionally exact copy of a metal-frame handgun. It is not.
Polymer-frame handguns are designed to be made from polymer, not metal, with the correct reinforcing in the correct areas to function properly when made from polymer.
The AR-15 lower receiver was designed to be made from aluminum, based on the specific properties of that material.
The Glock G19 fires 9x19mm handgun cartridges, the AR-15 fires 5.56mm rifle cartridges, which have very different characteristics.
This argument has been shown to be inaccurate in multiple previous threads.