The new winchester 777 primers have made a big difference in my gun with the crud ring. If you can locate some, try them.

And I too, swab between each shot at the range. Why not? With any bullet/powder combo it gererally improves your accuracy. And that first shot at game is with a basically clean barrel. I do "foul" mine when I load it by popping a cap by itself, then popping a cap with 10-15 grains powder, then swabing then loading. Has worked for me