WestKentucky
Member
I’m putting together a new upper. Upper reciever is a BCA and the pin slot looks pretty narrow compared to what I’m used to. The barrel is an old carbine barrel that was laying around, and similarly the index pin looks a bit large. So tolerance stacking isn’t going my way right now because I believe both are likely in spec, just at the edge of spec. So how tight is too tight of a fit? Currently the barrel does not seat. The pin hits on the corners of the slot and it appears I have roughly 10-15 thousandths that need to be removed for a snug fit. Pic is terrible. I will try to get a pic with better lighting.