I just got this 81 and have a question about the buttstock fit.

Does this look like a replacement or did the factory send out guns fit this way?
(I'm used to the fine wood-metal fit of the 8s)

Also, can you tell me about these 3 marks on the bottom of the reciever - sorry, pic didn't come out very well - these are 3 identical symbols, like a loop in a string

