Hmm: I'll bear that in mind next time I field strip any of a number of things that have welds on them.
Never saw any of the M-14 clones made from M1-A's with the selector lug welded on? That weld is in about the same area as these two tiny cracks are located. And before you moot it... none of them are re heat-treated after welding. You simply weld fast and keep the rest of the areas cool.
Or any of the M1 Garands made from two demilled receivers welded together?
Or any of the (Thompsons, Stens, Sterlings, MG-42's, MG-34's etc,. etc, etc) that have been rewatted?
It is not for the foolish... but it's not to be ruled out either. To each job the correct technique.
"So what happens if you were to use the reciver that is cracked and you happen to get a hot load"
Uhh... nothing at all. If you knew the Garand you would know that. "Hot Load" meaning 45 grains of Bullseye? If it'll blow this up,. it'll blow up your Model 70 too... But as I said, I expected a load of armchair experts to want to argue.....
Fact of the matter is that you could REMOVE all but the front TWO INCHES of a Garand receiver, chamber a round, lock the bolt into the bolt recesses, and fire it without an Op-Rod and you would be as safe as a baby in church. Hot loads or not... did you actually LOOK at where the cracks are, and do you actually UNDERSTAND how a Garand works?