hmm - it's interesting to see how much narrower gaps you guys use. To be exact, I use .047 (1.2 mm), and my crush looks very much like the one on top of p.282 in the latest edition of How to Brew. I might add that this setting is what most homebrewers I know here in Norway, use. Few, if any, go below .04. May the difference in kernel size between European and US barley varieties really be that big?
Palmer maintains that crush is not a very important factor infuencing yield - or need not be. He cites an experiment he conducted with help from Briess, that showed no conclusive difference between different grinds. (p.283) He says that when homebrewers in spite of this often report big differences, one explanation may be that a coarser grind requires more time. This seems right to me, based on my own experiences.
As for the risk of increased tannin extraction, that will depend on several factors; time, temperature and pH. A short infusion mash at 150F with care taken not to oversparge, will minimize the risk. But if you skirt the limits on any or all of these factors, then the shredding of the husks may matter. I guess that with ordinary good brewing practices, you can get away with shredding the husks
.
Brad Smith warns against the dangers of tannin extraction when using a fine crush, but he doesn't cite any sources. He's not the greatest of authorities, I guess. But there's a couple interesting comments there.
http://beersmith.com/blog/2015/10/2...ains-oversparging-and-hot-sparging-your-beer/