Calamari -- When dove shooting and shots are inside of 40 yards, I prefer the No. 7 steel pellet. Dove are pretty fragile (when you put the pellets on the front end) and the No. 7 steel pellets help to maintain good pattern density and they seem to have enough energy for dove out to about 40 yards. However, if my shots were getting out around or past 40 yards, the No. 6 steel pellet would probably be a better choice since it provides a little more down-range pellet energy.
Here are a few of my pattern numbers to give you an idea of the kind of performance I get from Win Xpert steel load.
Pattern results from a 20-gauge Browning Citori with 28" Invector-plus barrels and Briley flush chokes (patterns average of five, 30" post-shot scribed circle, yardage taped muzzle to target, and in-shell pellet count average of five).
30 YARDS / Xpert Steel 3/4 oz #7 steel (327 pellets) / pattern SK / 221 (68%)
30 YARDS / Xpert Steel 3/4 oz #6 steel (231 pellets) / pattern IC / 181 (78%)
40 YARDS / Xpert Steel 3/4 oz #7 steel (327 pellets) / pattern IM / 197 (60%)
40 YARDS / Xpert Steel 3/4 oz #6 steel (231 pellets) / pattern F / 165 (71%)
For bobwhite quail shooting, my preference is for the No. 6 steel pellet. Yes, a No. 7 steel pellet can kill them if they are close, but they don't always hold until you kick'em up. And, since most shots are at going-away angles the larger pellet provides more pellet energy and better penetration for those angles. When hunting over good pointing dogs I would normally use a CYL/M choke combo but if they are flushing wild I would go to a SK/IM or IC/F choke combo.
Pattern results from a 20-gauge Browning Citori with 28" Invector-plus barrels and Briley flush chokes (patterns average of five, 30" post-shot scribed circle, yardage taped muzzle to target, and in-shell pellet count average of five).
20 YARDS / Xpert Steel 3/4 oz #6 steel (231 pellets) / CYL / pattern 200 (86%)
30 YARDS / Xpert Steel 3/4 oz #6 steel (231 pellets) / M / pattern 204 (88%)
30 YARDS / Xpert Steel 3/4 oz #6 steel (231 pellets) / SK / pattern 173 (75%)
40 YARDS / Xpert Steel 3/4 oz #6 steel (231 pellets) / IM / pattern 155 (67%)
30 YARDS / Xpert Steel 3/4 oz #6 steel (231 pellets) / IC / pattern 181 (78%)
40 YARDS / Xpert Steel 3/4 oz #6 steel (231 pellets) / F / pattern 165 (71%)
For large upland birds like pheasant and grouse, larger steel sizes like No. 3s or No. 2s are proven performers. With big birds and the possibility of longer shots, I prefer these larger steel pellets as long as they are choked to maintain good pattern density for the distance used. That said, the #4 steel pellet would be a compromise quail/pheasant pellet.
Pattern results from a 20-gauge Browning Citori with 28" Invector-plus barrels and Briley flush chokes (patterns average of five, 30" post-shot scribed circle, yardage taped muzzle to target, and in-shell pellet count average of five).
20 GA 3" REMINGTON NITRO-STEEL MAGNUM LOAD
1 oz #4 steel (191 pellets) @ 1,330 fps
30 YARDS / SK / pattern 134 (70%)
40 YARDS / IM / pattern 147 (77%)
20 GA 3" WINCHESTER DRYLOK STEEL LOAD
1 oz #3 steel (145 pellets) @ 1,330 fps
30 YARDS / SK / pattern 114 (78%)
40 YARDS / IM / pattern 106 (73%)
20 GA 3" REMINGTON NITRO-STEEL LOAD
1 oz #2 steel (118 pellets) @ 1,330 fps
30 YARDS / SK / pattern 101 (86%)
40 YARDS / IM / pattern 99 (84%)
Using a 12ga would help all of the above pattern numbers, but I prefer to use my 20ga for upland hunting.
Hope this helps, good luck.