N.S.W. Permanent Artillery Force
This is a gilt brass uniform button used for the Permanent (paid) Artillery Force, whereas the whitemetal version (see below) was used for the Volunteer Artillery.
Both buttons are backmarked C. K. Moore, Sydney. He was a supplier of uniforms.

Queanbeyan Age (NSW), 30th October 1873 page 6.

Australian Town and Country Journal (Sydney), 29th March 1873. Illustration of practice manoeuvres between Permanent and Volunteer artillerymen.