Howdy,
I ordered a set of springs for my 311 16-gauge and Trapper Gun only listed the 311 without consideration of gauge, so I'm guessing they will work. I haven't torn mine down, yet, but the only springs that came in the kit were reduced power cocking lever springs.
The biggest trouble with using the 311 or Russian Baikal (Remington SxS and Stevens 411) is that the springs in the action want to close the barrels about 1/3 of the way. Long barrel have enough weight to hold the action open, but a coach gun will not be open for your shells when you try to shove them in under pressure.
I prefer the Stoeger for CAS. It only requires that the action lever spring be relieved and a little chamber polishing.
Bitterroot