i've killed a lot of deer and hogs with those rifles. The guns are very dirty, especially when using 209 primers. Changed mine over to #11 caps and it stays much cleaner.
Recommendations:
1. Can the pellets and use Pyrodex, 777 or Black MZ powder.
2. Install nipple for #11 caps and use magnum caps.
3. Try a few sabot/bullet combinations. i use the 250 grain SST in the crush rib sabot.