The only problem I ever saw, that was verified, was shooting ChiCom 7.62x39 copper plated iron core bullets from steel cases. All lead core bullets or brass cased ammo, while pressure was greater than spec 42,000 cup, were less than what .243 Win pressures. But at least my Redding die set allows you to load either .308" or .311". And .308" bullets are cheaper, but not as cheap as cast.