He should be fine. As long as they are not banned by name - or do not have more than two "evil features"... they are legal.
"Evil Features" are ok on a rifle made before 1994 so long as it is not banned by name.
Given the fact that Mass gun laws are even more strict than CT - I think he should be fine.
Please note I'm not a lawyer - but this is my interpretation of the CT laws. We don't require any sort of special paperwork or ID cards for long guns/rifles/shotguns.
Federal law would also cover him assuming he was traveling to a place where they were legal - and was just "passing through".