I'm left handed and the BPS has been my go-to shotgun for decades, particularly for waterfowl. I would guess I've owned 8 or so over the years. IMO they are the best LH friendly shotgun, but they are also a very old design and with the bottom eject action, by definition one of the most complex pump shotguns ever made. As such they have some quirks & design flaws.
First off, they are made primarily from steel so they are heavy compared to most any other current production shotgun. I'm sure you already noticed how heavy the Upland Special is for it's size, I believe they are 7.5-8 lbs in 12 gauge. My 3.5" 12 gauge with synthetic stock & forearm comes in around 8.5 lbs or a touch more. Not an issue in a goose blind and helps soak up recoil, but not optimal for a couple miles of walking up roosters.
When the action is cycled the fired round ejects and the new round isn't released from the magazine onto the shell carrier until approximately the last 1/4" of pump travel. You can slowly cycle the action and see how this works. Because of this, it takes some practice not to short shuck a BPS, particularly when like me you use primarily 3" shells in one chambered for 3.5". On the plus side, the bottom eject protects the action from the elements and empties eject right at your feet.
Putting a BPS back together after taking it down for a thorough cleaning is a PITA compared to any other shotgun that comes to mind, far too much for me to describe here. Suffice to say it is not intuitive. There are videos on Youtube that show how to do it. One tip, the half moon pin in the trigger group has to be perfectly lined up with the grooves in the receiver or you'll never get it in the action. The secret is the pin can be turned by hand to line up. I've known instances of guys not figuring this out and taking their BPS to a gunsmith to put it back together.
My biggest peeve with maintaining the BPS is the magazine tube and tube stop. For reasons no one has ever been able to explain to me (and I've called Browning about it) the magazine tube is made of ridiculously thin steel, uses a friction fit tube stop, and has extremely fine tube cap threads. I suspect it has to do with how old the design is. If they ever changed this to a tube as robust and KISS simple as that on an 870, I would never complain about maintaining a BPS again, and if it were an upgrade option I would send my BPS to the factory tomorrow.
To take the tube spring out to clean (the spring and inside of the tube rusts if you don't do it periodically) requires the tube stop be removed from the tube mouth via a large C-ring pliers to compress it or prying. Of course, no one has this tool, so the stop usually gets pried out with a screw driver which invariably damages the thin steel/threads at the mouth of the tube. Again, w/o the correct tool, after cleaning the stop gets tapped back into place, then the mouth of the tube is sort of peened back in to retain the stop. If you are lucky, with several tried you can get the tube cap screwed back on. If you're ham handed and dinged up the mouth of the tube too badly you won't be able to get the cap screwed on, so get thee to a gunsmith for a new mag tube.
The fly in the ointment is that we lefties don't have a lot of options when it comes to shotguns. We either shoot right handed shotguns (as a kid who grew up in the 60s when LH shotguns didn't exist then later as a 40 year LEO where RH 870s were our standard heavy weapon, I learned to run a RH pump shotgun to the point that I find a LH shotgun clumsy), or we can go with the cheap LH 870 or Mossy or a ridiculously expensive LH auto. Given that, the BPS is the best LH user friendly shotgun out there...
