CBF125 caliper bolt issue

[Killer Rat]

The bolts on the front fork are 8x25 which leaves a 1mm gap on the inside of the fork to the disc. The bottom bolt used to keep rubbing against the disc bolts so i decided many moons ago to file it down so it wouldnt rub.
Today after fitting the new front tyre, i decided to check the disc for warping on a glass surface. The disc is still true, and also the front wheel is true with no play.
On turning the wheel i had significant rubbing from the bottom bolt onto the disc bolts, was wondering if it's possible for the bolts to become stretched over time? anyway tried to file the bolt down again and snap!

Anyway my issue is that ideally i need to ensure only 23mm of bolt goes in which will fully secure the entire threads without protruding and looking dangerous.
What kind of 2mm washer should i use for this 8x25 flange bolt to be safe and secure.

Thanks in advance.
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No! No more talk! We go in! We kill! Kill! We kill 'em! They kill us, we kill them! Kill 'em! Kill 'em! Kill! Kill!
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cbf125 09', cbt passed 4/6/2010 - 28k miles - 1 major breakdown (stator)

[YBR Ric]

You could use an 8mm Stainless DIN9021 washer which is 2mm thick, but it's also 24mm in diameter - although that's easy enough to rectify if need be.

I used a pair purchased from Westfield Fasteners as shims to centralise my Pretech 6pot over the disc rotor.