cartridge receiver
cartridge receiver
[′kär·trij ri′sē·vər] (ordnance)
An item integral to a carbine, rifle, or shotgun, designed to take the charge from a cartridge magazine or clip or a single cartridge or shell and hold it until chambered.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.