Flash Hole size?

I saw this on another forum:
The name of the game is that the smaller the port in your nipple is, the smaller your group will be. The reason is that the bigger the hole, the more inconsistent your velocity, which affects your group size. If your hammer blows back, you have long passed any accuracy your rifle had. So, if you are experiencing accuracy issues, the first thing to do is REPLACE YOUR NIPPLE!!!! As a ballpark figure, for long range (95gn+ powder, 600gn bullet) start with a .5mm hole, replace at .75mm. For short range (50 - 70gn powder) replace at 1mm.

Is this true? I always want the bestaccuracy.

Wow I wonder who was blowing that smoke! New nipples probably have a flash hole about .030" (.762 mm) and should be replaced once it opens up to .035" (.889 mm).
Differences in bullet weight, powder charge (by weight), and loading technique have a far more adverse effect on accuracy than a couple thousands of an inch in flash hole size up to a point. If the flash hole gets too large you could run into inconsistent ignition issues.