; and (B) does not include an attached tubular device designed to accept, and capable of operating only with, .22 caliber rimfire ammunition. . (b) Related definitions Section 921(a) of title 18, United States Code, as amended by subsection (a), is amended by adding at the end the following: (42) The term barrel shroud — (A) means a shroud that is attached to, or partially or completely encircles, the barrel of a firearm so that the shroud protects the user of the firearm from heat generated by the barrel; and (B) does not include— (i) a slide that partially or completely encloses the barrel; or (ii) an extension of the stock along the bottom of the barrel which does not encircle or substantially encircle the barrel. (43) The term detachable ammunition feeding device means an ammunition feeding device that can be removed from a firearm without disassembly of the firearm action. (44) The term fixed ammunition feeding device — (A) means an ammunition feeding device that is contained in and not removable from or is permanently fixed to the firearm