How was their quality back in mid 80s? Any idea?
I have no first hand idea. My father says that they were okay to pretty good during the mid 80s, but that they had some spotty QC issues. DPMS from the same era was pretty bad to marginally acceptable sometimes, mostly on the bad side.
Dad says that back in the 80s, the hierarchy was Colt, Bushmaster, then everyone else. During the late 80s, Bushmaster passed Colt.
Back with my knowledge now: These days, Bushmaster is very popular, based on the reputation of those 80s and 90s rifles, but they’ve been slipping a bit of late. You can get better rifles for the same or less elsewhere. The advent of really cheap CNC machining gear has really been a game changer in the AR field.