My 28 gauge RBL has 26” barrels and is chocked IC IC. I mainly use it with #9 shot Spreader RST’s over the dogs hunting Mearns quail.
I generally also change shells rather than chokes. I used 7 1/2 shot on these Gambles, but will be using 9’s later on Mearns.
Late season desert birds as well as pigeons and Eurasian dove sometimes 6’s. Although I will shoot what ever I have on the Eurasians.

Phil, I have hunted and taken Gamble's near Tucson, at Rail X, but have never had the opportunity to try for Mearn's. I'm curious why the shot size change from 7 1/2s on Gamble's to 9s on Mearns. Closer flushes with the Mearn's?

Stan the Mearns generally flush a little closer, plus they are not near as tough.
The desert birds. Gambles and Scales are darn tough. I have know to shoot 6’s during the later part of the season on mature tough birds. Knock down one of these desert birds and they will bury in Cactus or crawl down a hole.