First; it would seem to be that as the gun recoils upward there could be a tendency of the barrels to want to tip open due to their inertia. Different makers compensated for this by various means.
I seem to recall reading at some point in the past that when applying pressure to tapered engaging points that friction will keep them from moving up to about 7°. Beyond that 7°, one is counting on the spring pressure to keep the bolt in place. I do not know what angle Stevens cuts their bolt to, but Lefever states in their catalogs after they went to this type of bolt it is cut on a 15° angle. I have never had one of mine show any tendency to open.
