Ok guys...not an AR pro here so I don't really know my way around the system well.
I have a spike's tactical lower and picked up a shrike upper. The front pin is in place but when I lower the back, the rear pin will only go about 3/4 of the way thru. Basically it goes thru the right side of the lower and the shrike but then won't go thru the left side of the lower.
I have pressed hard with my thumb and cannot get it any farther. I have an AR57 upper that fits easily. Any thoughts? I don't want to go at it with a hammer. Kidding...kidding.