The United Kingdom has become the first nation in the world to receive a modern cased telescoped ammunition (CTA) automatic weapon, the French 40mm CTCS, according to IHS Jane’s. The UK procured the weapons in July of last year to upgrade their Warrior IFVs, and as the main armament for the new Ajax scout tanks, expected to enter service in 2017.
The 40mm CTA weapon utilizes a wheel-like chamber, similar to that used in the famous Heckler & Koch G11 rifle of the 1980s and ’90s. Ammunition is fed nose-first through the side using a rotary presenter and rammer arrangement. Despite its 40mm caliber, the CTCS gun is only about the same size as the 30mm Mk. 44 Bushmaster II cannon used on some armored vehicles and ships, and only a little bit bigger than the 30mm RARDEN cannon used in the Warrior IFV currently. Therefore, it offers a significant firepower upgrade to light armored vehicles like the Warrior.
The 40mm CTAI CTCS is maybe not the first telescoped ammunition gun to ever enter service, but it is a milestone in that it is the first CTA firing automatic weapon to enter service that utilizes modern ammunition designed to be more compact and lightweight.
An evaluation of the CTCS gun from all the way back in 2000 can be found via DTIC, here (warning: link begins a download).