I used to have mk85 but never shoot over 100 grs of powder,I would shoot about any grain bullet I put in it pretty good,I shot bullets from 180 grs to 250grs,It shot so good that I never saw the need to try more powder.I do think that most ML gives the max load as 120 grs,and some say 120grs powder or 150 gr pellets.Hope this helps
I wish I still had my m-85