Are billet receivers advisable for precision long range 6.5 Grendel build?

[Frontier Gear]

Another thing to remember is that the billet that a receiver is cut out of was forged to a size to begin with. It may not be forged to the extent of a forged receiver but billets are forged to size and shape and then cut to length.

This is correct. LRRPF52 is correct as well.

More important than forged vs billet are these two things:

1. How thick is it?
   
2. What alloy is it?
   

There is a huge difference between 6061 and 7075. However, for the purpose of a receiver, I don't think that it matters a whole lot. My biggest concern with the alloy type is actually where the charging handle "clips" on the upper receiver. 6061 is soft(er) and "wears down" a lot faster than 7075. That looks like a wear point to me. If that little shelf wears down from the charging handle hook and spring, then you pretty much need a new upper receiver.

Both forged and "billet" receivers start out as aluminum plate and are forged into that plate. In this case, the purpose of forging the receiver is to get the rough shape as close as possible to the finished dimension in order to minimize machine work. The added strength benefit is marginal. Let me explain why. I worked in an aluminum foundry for over ten years. Here is how aluminum plate is made.

All aluminum plate is cast. Depending on the mold the thickness can vary, but it averages about 1.5 FEET thick. From there is it heated back up to 900 degrees (it melts around 1,200) and then rolled (forged) down to it's final thickness. So in the case of an AR receiver, this would be about 1.5-2 INCHES thick. That is a LOT of forging. After rolling to final thickness, it is then heat treated and quenched. The "T6" in "6061T6" aluminum is actually the heat treatment, not the alloy type. Immediately after heat treatment it is then stretched. The stretching aligns the plate and actually helps to harden it. This is what is meant by "work hardened". After stretching, every square millimeter is scanned by ultrasonic inspection. They inspect the complete thickness of the plate for any abnormalities or voids. If it passes inspection it is then put into an aging furnace that further strengthens the metal.

My point being that the very small difference that is accomplished between "forging" a receiver from a 2 inch thick plate verses machining one from a two inch thick plate is not even worth mentioning as compared to the process that the plate has already gone through. Again, for our purposes.

1. How thick is it?
   
2. What alloy is it?
   

Another side note, "Aircraft grade" aluminum is simply a marketing scheme. Airplanes are made out of a lot of different types of aluminum. It depends on what part you are making. Is it a wing or a seat back try?