Obviously depends on how hard you push it, but one bloke ive talked too is still getting really good accuracy with 1000 rounds on his, Id be happy to get to that. Im planning on running it a bit back from max to hopefully get a better life. Im picking if you pushed it real hard, 500 rounds could toast it.
Ive heard reports of 5 firings, primer pockets losen up. Once again depends on how hard ya lean on it.
You dont build something like this for the economics of it eh, that would be like buying a twin turbo charged V10 Audi RS6 then moaning about the fuel consumption ;-)