Free: Contests & Raffles.
For grouse...Cylinder and IC for a double.IC for auto's and pumps.Use all season.
Haven't shot any birds yet but using mod on my 12 pump has been very successful in skeet sessions.
My preferred upland gun is a 20ga SxS. For pheasant on the WW Release Sites I use CYL, & IMP CYL and Prairie Storm #3, & #4 steel. For grouse & rabbits it's usually IMP CYL, & MOD with #6 or #7½ Pb.
I had a really nice Lefever 12 double choked cyl/full, and for open country covey birds (huns, chukars and the occasional wild rooster), I did most of my killing with the full choke left barrel at 40-60yds. The cylinder barrel proved to be almost useless unless the birds were at my feet. So, unless you're hunting grouse, lm/f or ic/m is a great all around combo, and if I had to pick just one, it would be ic/f. I had my Masquelier 16 hammer gun outfitted with a permanent Briley ic choke sleeve in the right, and sk, mod, and full tubes for the left, so I can use it for skeet and for upland birds. I like skeet in the left barrel for skeet shooting, since the second shot on doubles is about 15 yds.