The only forged receivers to date are military receivers (USGI and the Italian ones made from USGI machine tools and drawings).
All the Cast ones are repros of the original, and vary in their quality. All of the original are top notch (unless they were damaged by rust or war).
for an example of a "modern" Garand receiver.
The original USGI receivers are available as receivers or whole rifles from the CMP. Why mess with cheesy copies?
For those who have had good luck with their aftermarket clones, shoot'm and have fun with them, and thank your lucky stars that you got one of the good ones.