I see.
I was envisioning "bolt lug setback" as something else - namely issues with the bolt lugs specifically, rather than the recesses in the action.
I imagine that for this to happen to the recesses in the action, all lugs would have to end up pushing rearward, the top and the rear lug included.
Anybody have actual measurements or good pictures of the "inletting" of the ramp to accommodate a big shell in a std. length action? Looking at my 416 (mag. action), doesn't look to be any more metal behind the lower recess than on my 404 or 500 (std. actions).