The payload in the little bores is so small you will gain nothing in the wa of improved patterns even with buffer.
Remember, a shotshell is a "system" of components. Buffer may help with certain kinds of loads.
I use a lot of buffer in the 12 bore.
Lots of room, lots of published data. I get #1, #2, #3, buckshot loads that pattern inside a 20 inch circle at 40 yards.
I also get 94% patterns on average with #2, #3, #6, #5, #4, plain and nickel lead shot at 40 yards with dense center cores.
(turkey koads)
I use new primed hulls, add the buffer with a vibrating tool. This is absolutely essential to fill ALL the air spaces between the pellets and vibrating is the ONLY way to do this.
I use a .665 choke by Primos.
You'll go nuts trying to buffer the 11/16 .410 loads. You have nothing to work with in the rat gauges, no room and worse of all no proper components.
I use special heavy wads for tungsten shot becasue they protect the lead better than any wad made for lead.
I've gotten killing patterns to 60s yard with #3 buck, but these are specialty loads for varmints, not quail or rabbits.
Nor Deer. The #3 and #4 buck loose too much gee whiz to try on deer past 30 yards.