Need info on 1916 DWM Luger

[gmlehmann]

Alright, I broke down the gun again and was taking another look at things and noticed the part located near bottom center of 1st pic. Is that a number or a marking? I thought it looks like a 55 but then the loops look strange to me going full circle. If it a number then I suppose it’s another mismatch. Could someone also educate me as to what the proper name for this part is as well, being new to this I have no idea.