The only two I can find in production are the Tar Hunt custom guns with an ER Shaw barrel or the Browning BPS Rifled Deer Hunter.
I believe Marlin, Mossberg and Browning got out of the bolt-action slug gun business. Savage still makes one, 1:35 though.
I'm not hung up on getting on, just curious. If 1:28 is better, why is there not more barrels out there with that twist rate?