It is an elongated 357 that has an OAL case length of 1.6. There is still brass floating around you can buy but I am not sure if there is any current manufacturer of loaded rounds. It was developed for sillouette shooting with the idea of shooting heavier bullets at the same velocities as normal 357. Unfortunately, some guys tried using light bullets and extreme velocities and some guns experienced a small amount of gas erosion above the forcing cone that stopped after small cut was made. These guns are the basis for 99% of the Supermag, Maxi or Long conversions you sometimes read about such as the 445, 414, 375, 475 and 500 longs.