Bighorn TL3 - true controlled round feeding w/ AICS magazine lips shortened

Controlled round feeding is achieved by the lower cartridge pressing the top cartridge up into the bolt face. The length of the feed lips must allow the body of the lower cartridge to press up on the top case base.

If the lips are too long they will need to be shortened as is the case here of .308 length factory lips with a 6.5 Creedmoor cartridge. If the lips are too long the neck of the lower case will be what pushed up the top cartridge into the bolt face. The neck diameter is too small to get the base of the top cartridge up under the extractor in slow feeding.

Some brands of aics-style magazines have shorter lips but this will still need to be checked. If the shoulder is pressing up on the top cartridge it will cause the top cartridge to jump forward due to the angle of the should. This will thus not result in cartridge being captured by the extractor and being “controlled” in feeding.