I had one as well, and used the exact same technique.Have one of the same vintage shot it for years with my hand under mag with slight pressure, feeds every round.
Seven High said:How is your AR-7 malfunctioning?
Yes have done. This is why I'm asking if anyone knows someone that deals with these AR7'sjsimmons said:Take it to a local gunsmith, and see what they say. Any gunsmith worth his salt can fix it. Before doing that, try buying a new magazine (or new mag spring)