Considering your requirement of brick-like reliability there are only a handful of sxs that will work. I know because Ive broken many different sxs guns shooting the snot out of them at targets. Your BSS meets the reliability criterion and at an excellent price point. Ive run a few 25 straights at skeet and wobble skeet with both my 12 and 20 gauge BSS shotguns with the original chokes. Both of them are LM in the right barrel and Holy Cow extra full in the left. Makes for nice soot balls. I shoot for fun and not score and have learned to enjoy tight chokes. Shoot what you have and see how it goes. Your other options are an original Winchester 21 (not a CSMC gun) or a nice, new Perazzi. 12 gauge 21s are relatively reasonably priced right now. The Perazzi is, well, not so reasonably priced, but an outstanding gun. If you can find a heavy framed Webley & Scott 700 in good shape that would work as well.
Have fun,
Jeff
