Those two pins are actually the ends of a single U-shaped part. That lock-up system is still used on all Beretta 68x-series O/U's today. It has been very successful.
In my experience, the parts that wore were not the pins but the holes in the monoblock that the pins fit into. With even a little wear, you can easily see that the holes are no longer round, they are oval, having worn on the bottom. As they wear, the top lever moves to the center and sometimes to left of center. The gun continues to lock up tightly, but eventually wear will cause the gun to pop open when fired. This is not a safety hazard, as the gun will open only a crack, and will not fire again while open. It is, however, a sign that the gun is overdue for an oversize locking lug. The lugs come in several sizes, and when the holes are too big for the largest lugs, they can be drilled out and fitted with bushings so you can start over with the smallest lug. Thus there is no limit to the number of times the locking mechanism can be tightened up to compensate for wear.
