I'm going to guess cutting off at 3 volts (as measure by a meter at the cell terminals, not at the cables or any other pieces of attached hardware) will net you about 5Ah less than actual capacity. So if you get 267, then I think you'd have a perfect 272Ah cell.
Thanks. I'm hoping these test out to 280ah since that is what I purchased.
On another topic my tester has the ability to run the battery test in Internal Resistance mode. Would that be helpful for anybody if I run that test for about 10 or 20 minutes on a battery that is at 50%? All my batteries are labeled IR .12 ohms.