Yes, it can be fixed with valve grinding compound.
What I did was to crush up some chromium oxide buffing compound and mix it with a little mineral oil.
I fixed two PPM's this way. But second one was so bad that hand lapping would have taken weeks with my abrasive paste. Chromium oxide buffing bars are very fine. I made a jig with which to turn the part with an electric drill. Maybe you can use something more aggressive.
Both my PPM's will drop hundreds of 223 loads of H335 without any grittiness and without spilling a single drop. That's my second finest powder. Longshot would be no problem, at all. H110 is still too fine for my PPM's, though. It just about works, but then after awhile, the grittiness starts to set in. I think one of them can just about handle it, but I don't want to take the chance of roughing up my measure, so I just use a dipper for H110.
If there is any measure that can drop H110 without grittiness, I would be impressed enough to go out and buy one - even though I'm done with the powder.