This is a Martini Henry Mark II Rifle made in 1878. It's a single shot rifle chambered in the .577/.450 Martini Henry cartridge.

The first shipment of around 1500 Martini Henry Mark II rifles to South Australia arrived in early 1878, followed shortly by a quantity of cavalry carbines. All were marked on the right side of the action with a broad arrow over SA over a number (commencing at 1). In addition, under the number was stamped either the letter S or L, indicating short or long butt. These rifles were issued to the Volunteer Military Force.

In addition to this, it appears the South Australian Police made separate purchases of Martini Henry firearms although they were marked on arrival in the same manner, and following on in number sequence, as those of the volunteer militia. This rifle (Rack No. 2566) is likely one of 200 purchased directly by the South Australian Police in 1881.

A total of 293 SA Police Martini Henry Rifles were sold (along with many other police firearms) to the Western Arms Corporation in California in 1953. This rifle (Rack No. 2566) is listed in the book “Service Arms of the South Australian Police” as one of those issued to South Australian Police and sold to the US.