A harsh grit blast would, but then all the sharp edges on the lug and bosses would be gone / damaged / nibbled away etc so I dont think thats the issue.
I am not a frame builder but IMO, the lug should be a very tight / flush fit in the first place rather than having a void to fill - the filler material should only be very thin.
I used silver solder (soft) to fix my forks and they blasted / powder coated perfectly with a very unforgiving gloss black finish - no material removed at all.