I did a five gallon batch of an Irish Red, allowed it to go through primary fermentation for ten days, transferred it to secondary for 7 days, then bottled. The recipe called for 3.64 Oz of priming sugar. I accidentally put in 3.94 because I read the 9 wrong. Should I be concerned about bottle bombs or over-carbonation in regular, 12 oz. amber bottles? The actual volume at time of bottling was 4.8 gallons, not 5 gallons.
Eh up Ben, I've been brewing for 25 yrs and i still worry about bottle bombs. but lets put this in perspective, if fermentation is complete- IE no change in sg for a couple of days and you don't over prime all should be well. All my bottles are stored in a cardboard box with packing, losing the beer is not the issue with me its not having to clean up a big mess if it ever did. its has never happened so if you follow the first two probably it probably never will. or use PET bottles for low alc quicky drunk beers, they can take a LOT of pressure,
You should always be worried about bottle bombs (or at the very least, over-carbed beer) if you cant assert that fermentation is complete before you bottle.
Buy a hydrometer and use it to assert that fermentation is complete (specific gravity reading stable for 3 days) before bottling. It removes guesswork from the process and thus anxiety from wondering whether or not today is the day your beer explodes.
In this particular situation, assuming that fermentation was complete, the small amount of extra sugar is unlikely to cause a bomb. However if you open a bottle and the contents fly out - get the rest in the fridge quick to stall fermentation otherwise you may end up with bombs.