1/2 pound at $70 sounds like retail pricing of R-12.
Being 1/2 pound down isn't necessaryily as bad sign, as that really isn't much in the whole picture. When was it last charged (if ever) would be my next question.
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72
'02 CLK320 Cabriolet - wifey's mid-life crisis
2012 VW Jetta Sportwagon TDI...at least its a diesel
Non illegitemae carborundum.