Here is your problem:
You are shooting steel headed shells.
Here is the fix:
Stop shooting them.


Brass is an elastic metal and somewhat self lubricating. When you fire the shell the head fire-forms to the chamber and relaxes somewhat allowing extraction, even if the chamber pressure is a touch high yet with a quick cycling action like most gas shotguns do.
Steel heads fire-form as well, only steel is not nearly as elastic so it doesnt relax as much as brass. It is not self lubricating like brass as well. Add to this the quick cycle and trying to extract while chamber pressures are still up there and the issue is compounded.
It also explains why it seems better when you CLP the chamber(Stop doing that too)
This is the same reason steel casings will stick in an AR.
Chances are your chamber is a touch tight compared to your buddies 930.
It can be measured and opened up if need be or you can stay with the brass headed stuff.