AK steel?

[ENTHUSIAST]

Specifically what type of steel was originally used to make AKs?

Is the trunnion steel a lower grade than the barrel steel?

[SJgunguy24]

IIRC the barrels are 4130 or 4140, the receivers are usually 4130. As for the trunnions, not sure. I did weld up one that had a small crack where the rivet goes in the mag well. It was an AMD and it flowed very well and was as good as new. IIRC Matt (Turbo this) uses 4140 that is heat treated for his trunnions.

[E-120]

This is just me guessing so dont put to much into it. But, the quality of the ore used in the barrels, trunnions and receiver should all be the same. No difference in quality like Japanese steel or S Korean, etc. Differing parts though will be either heat treated or processed differently.

[bodiebill]

Steel quality

Quality of steel will vary greatly from one producer to another. It is not the ore that is the criteria, but a myriad of quality control methods and techniques, equipment, the skill and dedication of the melt shop crews, etc.
Much of the steel used today in the arms industry is electric furnace steel which is dependent on the quality of the scrap and alloying additives.
Steel making is a complex operation, and quality varies greatly around the world.
Even when you are told that it is 4130, etc. the quality can vary greatly among steel makers---some are well known for high quality, and others not so high.
Some is "Seiki highest quality" steel and then there is HF quality at the lowest price with comparable quality.