The Browning pings is due to a slow mute of the receiver. This can be extended or even made adjustable in duration by changing the value of an electrolytic on the receiver B+ line going thru the T/R relay. It occurs during Tx keying not at the end of transmission like a roger beep.
I can recall two Lafayette CB models we sold with the same unique mike, where the ping happened going from transmit back to receive. The fix was to adjust the spacing between the leaf spring contacts in the mike head. The leaf springs in this mike were extremely thin and easily bendable without too much pressure. About a year later, the mike was replaced with something a lot more durable.