Hello fellow k/ommando's

Im needing some help in picking my next shotgun.

As my name implies im british, but have moved to the states, and now that i pay taxes ect ect and being a gun nut. I recently purchased my first shotgun (stevens model 320 combo version)
And i have already put around 500 rounds through it without problems, including 2 3/4 00 buck and slugs as well as 3 in 00 magnum loads just for shits and giggles

At this point im looking for a decent semi auto shotgun to add for my collection but cannot decide what i should get. I would love to hear your opinions and ideas. I was looking at a mossberg 930 security but i have heard alot of flak regarding its reliablilty and issues chambering even 2 and 3/4 loads.

This brings me to my last question. I will be using the model 320 for home defence and have am using multiple shell types in my mag tube. Currently my config goes:
2 3/4in small game load (warning shot)
2 3/4in 00 buck (should have listened)
3 in 00 express magnum (make my day)
Followed by 3in buck shots

Can or should i tweak this?


Looking forward to responses

Kindly,
Your armed english gentleman