popplecop;
I too would be extremely leery of using one of these, especially with modern SAAMI spec shells. I presume they did pass proof for use with the shells of their day. Obviously that one rear lug in the bridge is not as strong as the two forward ones locking directly into the front receiver ring.
In the shotguns built specifically as bolt actions using the lug as the base of the handle, they were designed with that function in mind. This rear lug on a 98 was not designed as a primary bolt, but simply as a reserve in case of forward failure. In the event the two front lugs began to shear the third would add re-inforcement, but I think it would be totally safe to assume it would never be required to handle the full load of firing in its original design.
Essentially I am in agreement with what you said, except to point out the rear lug was independant & not a part of the handle.
