Cleaning up an old 1100 for a friend of mine. He got it new in 1974. My question is about the locking block. All the other ones I have seen have used a roll pin to hold it in the bolt. THis has a tiny little part that is loose. It looks kind of like the head of a nail with a little tit on it. THe little tit goes into a hole in the locking block. I am assuming it is factory as my buddy never disassembled the bolt. Was the roll pin a later improvement? Should I change out the locking block for a new one with a roll pin? Thanks.