Aaaggghh! I wouldn't use those in the picture. It's worth getting new proper ones, because they're made out of a suitable composition of steel and they haven't been butchered or stressed.
For the bi-hex heads a 1/2" socket is often a more of a tight fit than a 12mm one, so is less likely to take the points off. Alternatively those irwin Bolt Grip sockets are very highly thought of on here, and if they can be persuaded onto the bolt may well do the trick.
Another reason why it's worth keeping the brakes at factory spec is that in the event of an accident, the police and the insurance company will go over it with a fine tooth comb and nonstandard components could spell trouble. One of the reasons Nigel Gresham went to prison was that investigators discovered inappropriate brake components (as well as a several other problems) so it's not worth skimping.
For the bi-hex heads a 1/2" socket is often a more of a tight fit than a 12mm one, so is less likely to take the points off. Alternatively those irwin Bolt Grip sockets are very highly thought of on here, and if they can be persuaded onto the bolt may well do the trick.
Another reason why it's worth keeping the brakes at factory spec is that in the event of an accident, the police and the insurance company will go over it with a fine tooth comb and nonstandard components could spell trouble. One of the reasons Nigel Gresham went to prison was that investigators discovered inappropriate brake components (as well as a several other problems) so it's not worth skimping.