It seems to me that this "strengthning" design came about in the third quarter of the 19th century. It was , possibly, a marketing affectation that was supposed to make the side to side motion of the barrels, at the breech, a thing of the past. Considering that I have never seen a gun that had them be loose in that direction, I think it must have worked.
As the leading edge of the clip must be sharp to fit the barrels, it is easy to see that some have been wounded by them.
I still think that they are attractive and knowing the skill necessary to make them, it should be a sign of an especially fine gun.
But as Russ was wont to say, I could be wrong.
Best,
John
