Purely from an experimental stance, I wonder if they could be shimmed up slightly with something like plumbers tape or maybe just a little surface coat of wax.
Have any of you tried the JSB 16.2gr pellets? Or the 13.43gr RDM? I had an experimental Huben K1 in .177 and the 16.2gr Beasts did the best in it. Might be worth a try.