Ive read that Barrels that are not for the TPX sometimes cause issues (not entirely sure why but have read that somewhere.)
Because the bolt is designed to basically enter the barrel when shooting. Aftermarket barrels not designed with that in mind might extend too far 'past the threads' resulting in the bolt actually slamming metal into barrel end... not good for either. This is also why bores smaller than ~.687 (barrel inserts?) also tend to inflict damage on the marker.
Well to be fair the TPX can handle FPS over 550. Ive shot 3 or 4 mags through mine doing well over 500fps and still didnt break paint.
People notice more breaks when their chronoing high - across the board regardless of paint or marker.
I noted the supposed increase in FPS in a TPX when switching to a lighter [TechT] bolt.
Ergo, make sure you re-chrono after installing bolt.
Paintballs themselves are designed and tested for ~300 fps performance.
Paintballs [if they were] designed to shoot at 500fps will inherently have harder shells [to withstand the increased impact/acceleration reliably], leading to more bounces @ 300 fps.
You can shoot at higher fps, your paint might even survive...
But if your wondering why your breaking paint...
That's the first place I'd look.