I don't know about other manufacturers, but I have a few L.C. Smith's that the lug (loop) was loose and on a few older "elsies" they put a short rib between the loop to the end of the barrels. The longer bottom rib and this shorter one helped hold the loop in place even if loose. Sometimes going unnoticed while shooting the loop pushed the bottom rib loose. Also on some of these earlier guns it shows a drawing of a 7-32 screw from in-between the top of barrels (under the top rib) down to the loop holding it in place.

[Linked Image from i.imgur.com]

Also on some of the beavertail for-ends there was a screw that went through the top of the for-end wood and attached to the for-end metal. Hunter Arms called this a Recoil Rod and was to relieve the recoil on the loop.

[Linked Image from i.imgur.com]

This print was for Regular framed L.C. Smith's and I did not see any drawing for the Featherweight guns showing this screw.