I know nothing of the Benelli but the 590A1 is a heck of a good shotgun, provided it's length is not a liability in your particular application. I have a friend who deals in lots of police trade-ins and has for years, not to mention the guns of that pedigree I've personally owned over the years. This parts-robbing in news to me.
“Nine-tenths of tactics are certain, and taught in books: but the irrational tenth is like the kingfisher flashing across the pool, and that is the test of generals. It can only be ensured by instinct, sharpened by thought practicing the stroke so often that at the crisis it is as natural as a reflex.” ~ T. E. Lawrence