How it was explained to me.
A cast receiver will last somewhere from 250,000 to 350,000 rounds. Currently @ 50 cents a round that's $125,000 to $175,000 to test the longevity of the cast receiver.
Plus the cost to replace the barrel every 5K to 10K rounds. Throw in a new bolt or two every other barrel change. Say $400 per barrel change times 25 to 60 times for the life of the cast receiver. $10,000 to $24,000. New bolt @ $250 times 15 to 30 times for the life of the cast receiver. That adds another $3750 to $7500.
The forged receiver is supposed to last yet another 100,000 rounds. That just adds to the cost of more barrel replacements and bolt replacement costs that you could potentially have to pay for to further test the longevity of a forged receiver verses a cast receiver.
Has anyone here on this forum ever complained about a worn-out cast or forged receiver. - Nope....
My experience has been:
I have one rifle that I have put three barrels on so far. About 15,000 to 18,000 rounds fired so far with that SAI cast receiver. Back in the day 1000 rounds of surplus was $129 delivered (1980's). A 200 round battle pack or two per Saturday for a more than few years. Resulted in an infected bursitis sac in the right shoulder, which required every other day or so drainage of the puss, and a pic line for antibiotics. Fun times.