If they are recessed allen key types then yes they do vary. Also the paint thickness made an otherwise correct binder difficult to fit in one frame of mine.
If the previous owner over-tightened they might have distorted the lug making it hard to get the binder in. You might need to do some careful work with a round file to correct it.
thanks for the info. whipped out my calipers and internal diameter is shade under 8 and the bolts i have are a shade over. Looks like i need to get some round files and maybe a slightly narrower diameter bolt.
also looks like the clamp is slightly bent in on both sides and will need bending back out slightly as well
