Bolt carrier bearing tube for rifle receiver
View Patent ↗A metal tube provides a bearing for a bolt carrier in a rifle. The tube is machined to provide openings and co-molded with a polymer outer shroud to form a lightweight composite upper receiver. The tube has an inner surface that supports the bolt carrier in its reciprocal motion during cycling of the rifle action during firing. The length and diameter of the tube are designed to prevent tilt of the bolt carrier during operation.
1. An upper receiver of a firearm having a bolt carrier, a charging handle, a fire control mechanism and a magazine, said upper receiver comprising:
a metal tube having a sidewall defining an inner surface supporting said bolt carrier and motion thereof between an open position and a battery position;
a polymer shroud surrounding at least a portion of said metal tube;
a first opening in said sidewall and a first opening in said polymer shroud overlying said first opening in said sidewall, said first openings defining an ejector port.
2. The upper receiver according to claim 1 , further comprising a second opening in said sidewall and a second opening in said polymer shroud overlying said second opening in said sidewall, said second openings positioned to permit engagement between said bolt carrier and said charging handle.
3. The upper receiver according to claim 2 , further comprising a third opening in said sidewall for receiving said fire control mechanism or said magazine.
4. The upper receiver according to claim 3 , further comprising a fourth opening in said sidewall for receiving the other one of said fire control mechanism or said magazine.
5. The upper receiver according to claim 2 , wherein said first openings are positioned angularly offset from said second openings about a longitudinal axis of said metal tube.
6. The upper receiver according to claim 2 , wherein said second opening in said sidewall of said metal tube comprises a slot extending lengthwise along said metal tube, one end of said slot being open.
7. The upper receiver according to claim 1 , further comprising a rail mounted on said shroud and extending lengthwise along said tube, said rail comprising a plurality of ribs oriented transversely to a longitudinal axis of said tube.
8. The upper receiver according to claim 1 , wherein said shroud further comprises an outwardly projecting surface positioned adjacent to said ejector port.
9. The upper receiver according to claim 1 , further comprising a housing extending from said shroud for receiving a forward assist button, said metal tube comprising an aperture aligned with said housing for permitting engagement between said bolt carrier and said forward assist button.
10. The upper receiver according to claim 1 , further comprising first and second lugs positioned at opposite ends of said shroud for attaching said shroud to a lower receiver.
11. The upper receiver according to claim 1 , further comprising a buffer tube radius for attaching a buffer tube to said metal tube.
12. The upper receiver according to claim 1 , wherein one end of said metal tube comprises screw threads.
13. The upper receiver according to claim 12 , wherein said screw threads are positioned on said inner surface of said metal tube.
14. The upper receiver according to claim 12 , wherein said screw threads are positioned on an outer surface of said metal tube.
15. A firearm having a bolt carrier, a charging handle, a fire control mechanism and a magazine, said firearm comprising:
an upper receiver comprising:
a metal tube having a sidewall defining an inner surface supporting said bolt carrier and motion thereof between an open position and a battery position;
a polymer shroud surrounding at least a portion of said metal tube;
a first opening in said sidewall and a first opening in said polymer shroud overlying said first opening in said sidewall, said first openings defining an ejector port.
16. The firearm according to claim 15 , further comprising a second opening in said sidewall and a second opening in said polymer shroud overlying said second opening in said sidewall, said second openings positioned to permit engagement between said bolt carrier and said charging handle.
17. The firearm according to claim 16 , further comprising a third opening in said sidewall for receiving said fire control mechanism or said magazine.
18. The firearm according to claim 17 , further comprising a fourth opening in said sidewall for receiving the other one of said fire control mechanism or said magazine.
19. The firearm according to claim 16 , wherein said first openings are positioned angularly offset from said second openings about a longitudinal axis of said metal tube.
20. The firearm according to claim 16 , wherein said second opening in said sidewall of said metal tube comprises a slot extending lengthwise along said metal tube, one end of said slot being open.
21. The firearm according to claim 15 , further comprising a rail mounted on said shroud and extending lengthwise along said tube, said rail comprising a plurality of ribs oriented transversely to a longitudinal axis of said tube.
22. The firearm according to claim 15 , wherein said shroud further comprises an outwardly projecting surface positioned adjacent to said ejector port.
23. The firearm according to claim 15 , further comprising a housing extending from said shroud for receiving a forward assist button, said metal tube comprising an aperture aligned with said housing for permitting engagement between said bolt carrier and said forward assist button.
24. The firearm according to claim 15 , further comprising first and second lugs positioned at opposite ends of said shroud for attaching said shroud to a lower receiver.
25. The firearm according to claim 15 , further comprising a buffer tube radius for attaching a buffer tube to said metal tube.
26. The firearm according to claim 15 , wherein one end of said metal tube comprises screw threads.
27. The firearm according to claim 26 , wherein said screw threads are positioned on said inner surface of said metal tube.
28. The firearm according to claim 26 , wherein said screw threads are positioned on an outer surface of said metal tube.