I'm reading that the Saiga-12 has less perceived recoil due to
the gas mechanism absorbing some of the blow. Is this simply
theory or is it really going to be something I would notice? My
Mossberg 12g (pump action, 18-1/2" bbl) has a good kick to it.
All other things equal (load, recoil pad, barrel length, gun weight, etc.), a pump, or a break-open shotgun, will have a "sharper" kick than any semi-auto, as the forces are transmitted directly to your shoulder through the stock with no delay.