Depends if the semi auto is gas operated, or recoil operated.
Yes as a rule gas guns are softer to shoot...then recoil operated ones...and both shoot softer then most pumps. But after all that been said...Stock design and fit has an awful lot to do with recoil too. A poor fitting gun will seem to kick twice as hard on you.
My Beretta A 400 Extreme is definitely the softest 12 gauge I have ever shot....Gas operated with 3 different kinds of recoil reducers built right into the stock plus a decent recoil pad. The times they are a changing and with shotgun design it seems to be for the better. Still love my 870 and Over/Unders thou...lol
Jim
Recoil operated guns (the old long recoil Browning system) use the actual recoil to cycle the gun. That transmits quite a bit of force to the shooter. Gas operated shotguns bleed a portion of the fired gas off through ports to drive a piston assembly. Recoil is somewhat spread out and is less noticeable to the shooter. Short recoil guns and inertia operated guns still generate considerable recoil close to the long recoil system but have a speedier recoil pulse. The gas operated are the most pleasant to shoot. All three or four styles are very reliable and good to hunt and shoot with.
Darryl
My 1100 Magnum is a pussy cat compared to my 870 Magnum with the same loads.
Darryl



























