LRB Arms and Chinese M14 receivers are the only forged commercial M14 receivers. The other forged receivers are those made by the Fab Four for Uncle Sam and those made by the Government of Taiwan. All other M14 receivers are either cast or machined from billet. That includes Smith Enterprise and Armscorp. But that does not mean a cast receiver is substandard. No way! I'd take a Smith Enterprise receiver in a heart beat.
Yes, forged is up to 20 % stronger than cast. That assumes you perform no other heat treamtment after forming. But, ALL raw M14 type receivers are formed (forged, cast or hot rolled into billet) then machined then carburized, quenched and tempered. Before forged USGI M14 raw receivers were machined they were normalized to soften them for machining. For newbies, when you soften a steel through heat treatment, you also reduce the strength.
The point being, all M14 receivers, regardless of the method of forming (forging, casting or billet), are heat treated after machining to obtain the desired strength, hardness and toughness. The steel molecular structure changes three times through the post-machining heat treatment process. I go into a detailed explanation of this in Chapter 7 of the free online book M14 Rifle History and Development at
www.imageseek.com/m1a