I've read of people trimming them down. How would you do this without deforming them?
grinding wheel, dremel, belt sander, or files are all good options.
Or go here and buy some if that seems like too much trouble.....
gas tube roll pin at Brownells
though if you are going to go grinding on your gas block, I don't see how cutting down a roll pin will be too hard.....
-rvb