Standard velocity 22lr can and usually does have bare lead projectiles but lead deposits in the barrel of high velocity and hyper velocity 22lr means most of these bullets are copper washed to prevent the lead build up. Since the Mini Mag line is considered High Velocity and a premium round they are plated bullets.
The Mini-Mag bullets are not truely jacketed but copper washed, unlike the CCI Maxi-Mag 22Win Mag V-Max which used a Hornady copper jacketed V-max bullet.
CCI does use non copper washed 22lr in rounds like the Quiet-22, Standard Velocity, Green Tag, Pistol Match and Select 22lr loads.