As stated above, you should swab between shots at the range. I swab with one patch moistened with a 50/50 mix of windex and rubbing alcohol, then one dry patch. I then fire a primer to dry the flash channel, and reload and fire. I recommend swabbing between every range shot. I also recommend loose powder.

My Traditions gun (a Remington Genesis) shoots the Hornady 350 gr FPB conicals really well. Assuming you don't have a scope/mount issue, if you can't get consistent results with the maxiball, try some FPBs. I use a charge of 100 gr loose Pyrodex.