Did you have one of these as a child? Perhaps you had one as your first gun?
These small air guns were manufactured by Yale Engineering in Sydney during the late 1940's and 1950’s.
The design was protected under Australian Patent No. 4926 of 1946. It has a 7½” screw out barrel, and a Crac-Ajac logo on the stock. Serial no. 192 stamped on the barrel. This example has clearly seen much use. I haven’t tried it out. I’ve seen photos of a few other examples on the internet but not many have survived. For the advanced air rifle collector or those seeking rare Australian made firearms. SN: 192