A rifle with an upper receiver and a barrel attached to the upper receiver and including a bolt carrier, and operating, buffer, and cooling systems. The operating system includes a cylinder and a piston coupled to receive propelling gases from the barrel. As the piston moves between retracted and extended positions the bolt carrier is moved between closed and open positions. The bolt carrier includes a weight movable within a guide frame between rearward and forward limits. The buffer system includes a compression spring in a tube attached to the upper receiver in abutting engagement with the bolt carrier. A partially fluid filled cylinder is attached to a coil of the spring and includes a piston and shaft. The piston is formed so that fluid in the cylinder restricts movement in one direction and allows free movement in a second direction.
1. A bolt carrier comprising:
a guide frame, where the guide frame has at least one guide slot, and where the guide frame has a long axis;
a weight, where the weight is configured to be inserted into the guide frame, where the weight has an aperture;
a pin, where the pin is inserted into the aperture and the guide slot, where the pin prevents rotation of the weight about the long axis, and where the pin limits motion of the weight along the long axis; and
a spring, where the spring is operatively attached to the weight, where the spring is configured to push the weight toward a rearward location of the pin in the guide slot, and where the weight and guide frame are configured to move independent of each other within a length of the guide slot.
2. The bolt carrier according to claim 1 , where the weight is cylindrical.
3. The bolt carrier according to claim 2 , further comprising:
a receptacle in the weight; and
a rod, where the rod engages a surface the guide frame, where the rod compresses the spring, and where at least a portion of the rod fits into the receptacle.
4. The bolt carrier according to claim 3 , further comprising:
a bumper, where the bumper is operatively attached to a front end of the weight, where the weight has a rearward position corresponding to a rearward position of the pin in the guide slot, where the weight has a forward position corresponding to a forward position of the pin in the guide slot, and where the bumper presses against the weight and a portion of the guide frame when the weight is in the forward position.
5. The bolt carrier according to claim 4 , where the guide frame has slots, where the material removed to form the slots has a mass about equal to the mass of the weight.
6. The bolt carrier according to claim 4 , where the buffer is a plastic material.
7. A rifle comprising:
a barrel;
an upper receiver; and
a bolt carrier, where the bolt carrier comprises:
a guide frame, where the guide frame has at least one guide slot, and where the guide frame has a long axis;
a weight, where the weight is configured to be inserted into the guide frame, where the weight has an aperture;
a pin, where the pin is inserted into the aperture and the guide slot, where the pin prevents rotation of the weight about the long axis, and where the pin limits motion of the weight along the long axis; and
a spring, where the spring is operatively attached to the weight, where the spring is configured to push the weight toward a rearward location of the pin in the guide slot, and where the weight and guide frame are configured to move independent of each other within a length of the guide slot.
8. The rifle according to claim 7 , where the weight is cylindrical.
9. The rifle according to claim 8 , further comprising:
a receptacle in the weight; and
a rod, where the rod engages a surface the guide frame, where the rod compresses the spring, and where at least a portion of the rod fits into the receptacle.
10. The rifle according to claim 9 , further comprising:
a bumper, where the bumper is operatively attached to a front end of the weight, where the weight has a rearward position corresponding to a rearward position of the pin in the guide slot, where the weight has a forward position corresponding to a forward position of the pin in the guide slot, and where the bumper presses against the weight and a portion of the guide frame when the weight is in the forward position.
11. The rifle according to claim 9 , where the guide frame has slots, where the material removed to form the slots has a mass about equal to the mass of the weight.
12. The rifle according to claim 9 , where the buffer is a plastic material.