Mark, just found your post. The triggers you have are "keg" triggers, meaning that they were probably purchased at the local general store, and shipped from the manufacturer in a wooden keg. I have had/seen two sets of triggers identical to what you show and the main springs do not have a cut out. Therefore I also believe that the spring was modified to serve as a replacement set. The shapes of the triggers indicate that they are not your common East Tennessee truck garden variety and suggest manufacture in the North, or perhaps England...in a stretch. This would also support the replacement theory. Nice triggers, tang and guard. Hope to see you at the over the log shoots. Cheers, Bookie