Mojo, same story with me. I've been CRHing for years without knowing anyone else did it until I accidentally found this website a couple months ago.
About the original question, I think in 1979 most who knew about silver in coins probably already hoarded them fifteen years earlier, in 1964 so there probably wasn't much CRHing in 1979. An example being my grandfather who stocked up on coins (mainly quarters) as soon as he found out they would no longer be silver. After he had 4 or 5 boxes of them, there wasn't much a point to get more when there were far fewer in circulation.