The mineral resource at Graphmada increased 41% to 20.2 million tonnes of large flake graphite at 4% total graphitic carbon.
Other initial drilling has discovered outcropping graphite at surface, with Bass looking at a potential strike zone of 4.5km.
In 2019 the company announced an exploration target of 86-146Mt.
Bass said it remains "committed to its aim of establishing a large mineral resource at Graphmada to facilitate progress of large scale mining and processing studies currently being undertaken".
Shares in Bass were down 14% to 0.6c in early afternoon trading, capitalising the company at $24 million.