Cased telescoped ammunition firearm with dual feed

A weapon for firing cased telescoped (CT) ammunition rounds in quick succession, comprising:

• a barrel;
• a chamber member that defines a chamber configured to hold a CT round for firing from the weapon, the chamber member being retained in a chamber carrier of a chamber carrier assembly and moving among positions including:
• (1) a firing position in which the chamber member is aligned with the barrel for firing the CT round, (2) a first ejection/loading position in which the chamber member is not aligned with the barrel for ejecting a spent CT round and receiving a next CT round from a magazine, and (3) a second ejection/loading position in which the chamber member is not aligned with the barrel for ejecting a spent CT round and receiving a next CT round from an ammunition belt;
• and
• a dual-feed structure including a belt feed cam, a magazine feed cam, and a feed mode lock, the dual-feed structure being configured and operative (1) in a magazine mode of operation, to engage the magazine feed cam with a slide of a carrier assembly to move the chamber carrier from the firing position to the first ejection/loading position during operation, and (2) in a belt feed mode, to engage the belt feed cam with the slide to move the chamber carrier from the firing position to the second ejection/loading position during operation, the feed mode lock being rotated between respective positions for mode selection and causing the slide to engage the belt feed cam in the belt feed mode and to engage the magazine feed cam in the magazine mode.