I hunt with old 16ga guns and have always used #6 for chukar, huns and pheasant and #7-1/2 for quail. I don't hunt grouse. Last season I bought a case of BOSS #6 for use on quail at the suggestion of the people at BOSS. I shot few quail last year (or much of anything due to injuries that kept me out of the field). The #6 BOSS crumpled roosters and chukar at moderate ranges, so it may be a little overkill for quail, despite what they suggested. I may move down a size in BOSS. I'm happy with BOSS, but it's expensive. I still have a lot of lead left but since I hunt areas where non-tox is required I grow weary of having to switch back and forth.