Whether it's a screw grip, rotary bolt, Treble Wedge Fast or what-ever type of bolting has nothing at all to do with the lock works. He called it a bar action, & that ones a pure unadulterated "Back-Action" lockwork. But then I think the vast majority of screw grip guns did have back action locks.

Miller/TN
I Didn't Say Everything I Said, Yogi Berra