problems with co2

the last 3 batches ive made have been over carbonated. im trying to bottle 5 gallons of beer here, not make a damn empire. the wort/uncarbonated beer tastes great but i keep messing up the carbonation, even with 4oz of table sugar. and before you say "the yeast isnt done eating...." just know that one beer was in the secondary (1.073 barleywine) almost 8 months and i just added 4oz priming sugar for bottling....is it a curse? i dont want my beers to be ass nuggets.



edit: i guess a better questions is how to calculate the needed carbonation for a brew....i have an online source for brewing calcs but it is gibberish to me so far.

help is needed/much appreciated.

What was your FG on that Brley Wine?