Denis,
Get me a FFL and I'll send you Jack's 870 Junior 20 gauge. He has out-grown it for skeet and hunting. There are plenty of mods at cheaperthandirt to make it a great home defense shotgun. Don't worry about the gauge, there are plenty of custom shot/shell choices that makes the gun formidable. The gun was given to us so we're just passing the torch.
Simple gun. Glad you made it back to LA...are you staying for the winter?