When I started shooting CBs the conventional wisdom was that you should index both case and bullet for best accuracy. So I started out doing it but it seemed unlikely that it worked and it was a PITÅ. So I shot strings of groups alternating between groups with indexed and not indexed. I couldn't see a difference in accuracy. So I stopped doing it and haven't indexed since. However, I was shooting a factory rifle that would average about 1moa for 5 shot groups not a full bore custom benchrest rifle that would average near .5MOA. My experiments were also limited to 22 caliber bullets.
It has been a long time since I ran that experiment and discredited indexing for my own reloading. But I still see indexing recommended in some writings about CB shooting. Maybe it really does help in the rarefied zone of .5 moa or maybe my old experiment didn't involve enough groups and was misleading.
Has anybody shot comparison strings of index vs. non indexed rounds that indicated that indexing improved accuracy -- even a little?