Interesting. My gunsmith says there is variation in headspace on anti x actions when I asked him if I could ship my barrels to him without it. I’m no machinist so I do what he says.
Correct me if I’m wrong but the only Defiance action that would work with prefit barrels is the Ruckus. I still send my Anti X action to my gunsmith when new barrels are getting chambered.
For a hunting rig, I wouldn’t recommend a Ruckus action if weight is a concern . It’s a tank.