Huben GK1 .25 tuning for Altaros & JSB - charts and data

Cheaper lead-frees :)
Less expensive is always good, but on a more serious question, are these lead free lighter and harder .25 pellets shooting more accurate than the typical JSB's,? I know "weevil" has experienced improved accuracy with the .22 GTO lead free pellets. Also is there any issues of jamming? I read on another post that one person said they have had jamming issues with the .25 GTO's?