The B-80 is a Beretta 303, the model that pre-dated the 390. All the parts swap back and forth except the choke tubes. Beretta used their Mobile-Chokes and Browning continued to use their original Invector chokes.
Browning made 2 versions. A steel frame/action and the "Super-Light" AL frame. Both had the square back. I'm 95% certain all the AL frame 12Ga B-80's are 2 3/4" only despite their AL frame Beretta 303 cousins being 3" capable.
By the time Beretta was producing the 390 Browning had discontinued the B-80 and introduced the 2 A-500 abominations "G" for Gas with gold accents in the engraving and "R for Recoil with red in the engraving. They only lasted 5-6 yrs and the Gold took their place 94/95-ish.
Regarding the OP, I'm a dyed in the wool gas operated semi-auto user. I started on multiple 1100's 2 3/4" 26" Mod for upland and a 3" 30" full for waterfowl. A S&W 1000 Waterfowler after that, and then my 1st Beretta, an early 303 with the mag cut-off lever on the starboard side of the receiver NOT the toggle-switch on the forearm. I've got a few each 302's, 303's in 12 and 20's and a fair pile of both 12 and 20 391's. I never did care for the sight picture of the square back of the 390's or B-80's.
I've been through a bunch of recoil operated semi's as well. I only have 2 left. A Franchi AL48 28Ga and a reasonably old 11-Remington 48 20Ga my dad liked. Tried a few A-5's along the way, an AL48 in 20Ga, and a smattering of Benellis. I've always thought the "weak link" in a Benelli was that very light return spring they house in the butt-stock. I realize it's light so they'll work with "everything" but they're prone to slowdown when it's cold, even with great synthetic lube. Then they beat themselves to death in fairly short order. When the 1st locking head pin breaks, your best be purchasing a bunch of spare parts as more breaking is eminent. If Benelli built a "field" version with a much stiffer return spring they'd recoil less, last longer, and be much more reliable in very cold weather.