One pound of sugar adds 40 points (that is .040) to the gravity of 1 gallon of must. Pressed apples have a gravity of about 1.050 (more or less ) so adding a pound per gallon will give you a gravity of about 1.090. That gravity is typical of a wine and translates to about 12 % ABV (close enough) Is that high? I dunno.. but 12 percent typically balances nicely against fruit flavors and the levels of acidity in apples... But this is no longer a cider .. It's a wine when it has that amount of alcohol...