quite a problem these......unless you don't mind resizing regular 4.5 & 5.5mm balls yourself. Iv'e found that degreasing Gamo lead balls first in acetone & then immersing them in strong household bleach creates an oxide surface that "grows" the balls enough to fit a bore of the size that allows regular ones to just roll down & drop out at the muzzle, after bleach immersion just leave them to dry out & the oxide will continue to develop for about a week .after this, best to coat them with oil to avoid getting bleach residue in the bore . other than this you can slightly deform them with a pair of pliers , this again will sit them in the breech rather than letting them roll out the muzzle but may impair accuracy, but probably not that much. as for .22 balls, I think Portugal or Poland might be the closest place to get them, balls made by Kolter seem to be a bit more uniform in size than Gamo but harder to find on-line. hope this helps.