Don't take my word for it here's the expert.
Martini Cadet Rifles by Ian Barger, 597 Rockvale Road, Armidale NSW 2350
The large actioned Martini-Henry rifles were used by the various colonial armed forces and police forces in Australia from 1871, originally in .450 calibre and in the closing years of the century in .303 calibre. These .303 Martinis were generally known as Martini-Metfords or Martini-Enfields, depending on their rifling pattern, and used the .303 cordite cartridge designed for the famous Lee-Enfield rifle used by the United Kingdom and its former colonies from about 1895 until around 1960. At the time of Federation of the separate Australian Colonies to form the Commonwealth of Australia in 1901, there was thus already a fairly long history of the colonies using versions of the Martini action as their standard military weapon.
These military Martinis were very heavy full-sized rifles, too large and heavy for the 14-18 year-old cadets in the various militias of the time. The first attempt to provide a special cadet training rifle appears to have been made by the Victorian Government in 1887 when they purchased 500 Francotte Patent Martinis in .297/300 calibre. Subsequent batches of these training rifles were also acquired by the West Australian and Commonwealth Governments. The Francotte Patent allows removal of the lock mechanism by the simple removal of a single split pin, as seen on the later .310 Cadets. The Francotte Martinis were made by A. Francotte and W.W. Greener, who introduced the stamping of a kangaroo on the top of the receiver, as found in the later .310 Cadet Martinis made by Greener and the Birmingham Small Arms Company (B.S.A.). Apart from the Francotte Patent and the kangaroo, the action resembled the Mark IV Martini-Henry in profile.
Not to be outdone, the New South Wales Government in 1891 introduced a miniature version of the Martini-Henry Mk IV rifle. Still in .450 calibre, these rifles were made by the Braendlin Armory Company of Birmingham, and were stamped "BRAENDLIN CADET CARBINE 500/450" on the barrel and came complete with a cleaning rod slung beneath the forend. The right-hand side of the action carried the typical Martini-Henry cocking indicator. A similar rifle, the .310 Westley Richards Cadet Martini, was issued in NSW shortly after Federation. This was also a miniaturized version of the Martini-Henry, and like the Braendlin, did not use the Francotte lock removal system.
In 1910 the Commonwealth Government introduced a system of universal cadet training, and issued the States with what is now known as the .310 Martini Cadet Rifle. These employed the Francotte Patent, and were made in the UK by both Greener and B.S.A. They were marked "COMMONWEALTH OF AUSTRALIA" on the right face of the receiver, and had the now-familiar kangaroo profile on the top. They were issued to all states and thus carry the various State markings on the buttstock and on the upper right corner of the right face of the receiver. The B.S.A. Martinis are generally considered to be better-made than the Greeners, and the later and more common B.S.A. version carried a superior rear sight, adjustable for both elevation and windage. The cartridge was an existing commercial round, the .310 Greener, a small-game and target centrefire cartridge about the same size as a Winchester .32/20 and fitted with a 120 grain heeled lead projectile.
Frank de Haas in his classic "Single Shot Rifles and Actions" says that B.S.A. made 80,000 of the .310 Cadet rifles, although I have a Queensland-marked B.S.A. rifle dated May 1912 that has a serial number of almost 83,000. The .310 Cadet rifles were withdrawn in 1921 and cadets issued with the standard military .303 Lee-Enfields, although the stored Martini Cadets were re-issued to the militia in 1942 when Australia was in danger of being invaded by Japan in World War II. A little-known sidelight of this development was the manufacture in Australia at that time of a copper-jacketted round for the .310 Cadet, as use of the original lead projectile by the Army Reserve forces would have contravened The Hague Convention!
After World War II, the Martini Cadets were sold to the civilian population - I can remember seeing them in disposals stores in the 1960s selling for the equivalent of $6.00. Large numbers of Cadets were sold in the United States and also New Zealand. In the 1950s and 60s, .310 Cadet ammunition was available commercially in Australia, but in USA the nearest available round was the Winchester .32/20. Some Martini Cadets would chamber the .32/20 without modification, but those with tight chambers were generally re-chambered.
This was not always an entirely satisfactory procedure, as the groove diameter of a .310 barrel, despite the designation, was .320, while the projectile in the .32/20 round was about .312 in diameter and thus tended to rattle down the oversize barrel. Perhaps the majority of Martini Cadets, both in Australia and elsewhere, have ended up being re-barrelled to suit commercially available ammunition. The most popular of these conversions have been to rimfire calibres, both .22LR and .22WRM, and to small-game centrefire calibres, especially .22 Hornet, .218 Bee, .222 Rem and .357 Magnum.
Some beautiful sporting stocks of highly figured walnut or maple have been fitted to these converted rifles, and I have seen photographs of some extraordinary customised Cadets fitted with such stocks and with the actions intricately engraved. Despite its antiquity, the Martini Cadet action is a strong one, and many shooters are intrigued, as I am, by its simplicity, safety, ease of use, ingenuity of design, and precision of manufacture. Many are still in use in Australia in the form of a smallbore target rifle, the Sportco Clubman, with a heavy .22LR barrel and aperture sights.
Pat