jadavisYou've got an awfully high horse. I'm a mechanical engineer. Would you like to argue tolerances? You sound like you don't have the slightest clue what clearance actually means. Just because you are a ski tech doesn't mean you always are right about skis.
Take a second to ask yourself it 120 equals 122 and I think you will find it doesn't. Why would you recommend brakes that are too narrow? That means you would have a brake that is too narrow... plain and simple. Why would you recommend brakes that are too narrow? 130 mm brakes happen to be actually 130 wide frequently (I measured my brakes and they are that wide plus or minus 0.05 mm). That leaves you a 4 mm gap on each side which is quite reasonable. Yeah they will stick out a little... but so will the 115 brakes after you make them fit around your ski. Lets say you bend them to 126 to give yourself 2 mm clearance on each side. That makes them stick out 2 mm less on each side than 130 mm brakes. I don't think 2 mm is worth the trouble of bending them which you would have to do a little because they are only 120 wide like you said. You admitted that brakes are made to stick out a little and 115 brakes just wouldn't on a 122 ski.
People like you who say get narrower brakes they'll fit are the truly misleading people.
Respectfully, what you have here is theory vs. practical experience. While you're talking about tolerances, have you noticed how most ski brakes fit together like sloppy spaghetti? The fit of all the parts together is incredibly loose, as a result you get quite a large range of what will actually fit. A movement of 1mm at the binding itself translates into a lot of movement at the end of the brake arm. I got some 115 brakes over a 132mm ski with the slightest tweak of the brake arms (basically I maxed out the "tolerances" of the assembly)
A narrower brake with a slight tweak will, 9 times out of 10, give a tidier, sleeker and more robust end result than a bigger brake that overhangs.