This is an interesting post or problem. I have three 4013's, the single stack on .45 frame, the 4013 TSW non rail, and the 4013 rail TSW(.40tactical). The the single stack shows more peening of the locking lug. The original posters pictures are of the single stack I assume. What is a big difference between them all is the barrel configuration. In the attached pictures, the barrel on the right is the single stack, it is 43% heavier than the TSW's 3.20 oz vs 2.24 oz. even with the milled slab sides. On the single stack barrel the locking lugs have a small chamfer or bevel on the edges, which reduce the contact area and shows on the alloy frame. I am not sure if this was a factory bevel or something a previous owner might have done.
