yep, closed breach...but there was still a "head space" to allow for openign and closing with a shell inserted...the dra back was after firing, the .256 could and would "jam" the breach from swinging out and /or the shell case from being extracted...(pressure & oil...) in the chamber casued LOTS of problems and issues...same went for other gun companies, not just a Ruger problem....I know,I dealt with the ammo company ( Winchester) back in the mid 70's when our shop chambered a few Dan Wessons revolvers (yes, revolvers, multiple chambers, all six shots...) for the .256 Win, and we had issues, ,,,,got together with Austin Behlert back then (may he rest in peace..) and he did the final 'vapor hone' on our cylinder chambers, and voila, no more problems with extraction.......only built a few, got written up in American Handgunner, and the "job": died a 'silent death.................oh well, another few moments of fame & glory......