Out to about 25 yards, most 410's handle grouse and ptarmigan just fine. The 1/2 ounce 2 1/2" load usually patterns better than the 3" load.

The long shot column does not hinder shooting on the ground, but the tiny inner core killing pattern & wide wounding outer pattern of the 3" makes the round suck much of the time.

I love my little .410 single for grouse, but would like a SXS for birds that fly prematurely upon approach. The 1/2oz. #6 load works well for me.
Loaded in .444 Marlin cases, even better. Shortened .410 wad over 12gr. Unique with 1/2oz. #6 and a .44 mag gas check crimped over the load as a top wad. Nice even patterning load and good to 30yards. In my little single, it is better than anything you can purchase.