early M1 rifle trigger

I was reading the post about the H&R trigger and found these photos of two revision 2 triggers, one has the "high hump" on the sear. The reason for this is unknown to collectors. I believe a gas trap rifle in the 11K serial range had one of these "high hump"
searsAttachment 102147Attachment 102148

It's surprising how many small changes were made without revising the drawing... usually in response to an AVO. That meant (A-something) Verbal Order.