They're tough and easy to shoot well, IMO, but not as tough as Win. 21. I bought a 30" barrel 12 about 16-17 years ago, after having had a 28" barreled one. I won the 2010 AA Class S X S concurrent at the NSCA U S Open in Tunica with it that year. The punches I earned from that kicked me into M class.
I opened the left barrel to the same constriction as what the right was, .018", and have killed many, many ducks with it using 1 1/4 oz. steel shot loads. I have shot it so much that the right barrel is now off face. That is why I say it is not as strong as a M21. i shim the hook with HVAC aluminum tape and just keep on shooting it. The hook on a BSS cannot be welded and built up because of some sort of solder that was used to build the gun. So, I shim it.