It's an easy thing to check actually. Try to swing the takedown lever into its release position. If you have a heck of time pushing it through the full 90 degrees, then you're holding one of the "corrected" models. If it swings easily, you're likely to have problems with the takedown lever popping out during live firing.

The occasionally reported problem of the firing pin striker snapping off does not appear to be specific to certain serial numbers, or so it seems based upon what I've been reading and what I've experienced first-hand.

By the way, I am a satisfied owner of a BG380, even though it took two trips back to S&W to get it right.

P.S. The correction to the takedown lever problem does not appear to be a new frame. Mine was fixed with the old frame still in place. Either they have altered the takedown lever itself, or they adjusted the "spring" that holds the takedown lever in place. I believe it is the former, rather than the latter, although I can't say for sure.