Depends on how anal you are. /ubbthreads/images/graemlins/grin.gif
During my benchrest shooting days w/factory REM 40X or custom chambers whether tight or not, I turned the necks. It was after a pretty lengthy sorting process. Only turned the ones that made the final cut. The rest were relagated to the hunting rifle.
Did it make a difference. I think it prevented that occassional flyer. Won my share of matches. However, reading wind and mirage was the key and by far out weighed any neck turning gains.
Just carried the habit over to the hunting rifle for a while. I don't do it any more though the chamber isn't factory but is standard.
Am doing some tests at the moment w/a 338 Win factory. Just dinking around trying to get the SD down a bit. Things are pretty good for straight, 0.003 max but SDs are a bit high. Am missing my steel yote at 740 way too often even though the 200 groups are in the 5s. /ubbthreads/images/graemlins/frown.gif
Heck, just try it and see. It's no hassle, and reasonable cost but I wouldn't spend the $ unless I was going to do it. more than once.
What may be better is a Wilson inside neck reamer. I use one quite often. Seems as though w/high pressure loads, the brass flows forward.