Operating system for small caliber rifles
A weapon system is provided. The weapon system includes a receiver and an operating group. The operating group includes a bolt at least partially housed within the receiver; an operating rod (op-rod) assembly arranged to axially translate within the bolt. The operating group also includes a carrier assembly, a bolt assembly, and a recoil assembly. The system further includes a hinge or pivot joint at a connection between the recoil assembly and the carrier assembly, a firing pin lock, an elastomeric cone interface between the bolt assembly and the receiver, a hollowed out piston, and/or tapering on the lug of the bolt assembly.
1. A bolt assembly for a rifle, the bolt assembly comprising:
a bolt having a bolt body with a forward end portion; and
a plurality of lugs extending radially outward from the forward end portion, each lug of the plurality of lugs having an outer lug surface generally parallel to a major axis of the bolt and having opposed lug sides, an aft surface, and an opposed forward surface, the sides and surfaces extending between the outer lug surface and the bolt body,
wherein a cross sectional width of at least one lug decreases as the lug extends from the bolt body to the outer lug surface,
wherein at least one of the opposed lug sides is arcuate along its length,
wherein the forward end portion of the bolt is constructed to be received by a breech-end of a barrel,
wherein the aft surface of the plurality of lugs is arcuate from the outer lug surface to the bolt body.
2. The bolt assembly of claim 1 , wherein the cross sectional width is measured from a first lug side to the opposed lug side on the same lug, the cross sectional width being substantially perpendicular to the major axis of the bolt.
3. The bolt assembly of claim 1 , wherein the cross sectional width is measured from the aft surface of the lug to the forward surface of the lug, the cross sectional width being substantially parallel to the major axis of the bolt.
4. The bolt assembly of claim 1 wherein a first cross sectional width between the lug sides and a second cross sectional width between the aft and forward surfaces both decrease as the lug extends from the bolt body to the outer lug surface.
5. The bolt assembly of claim 1 , wherein at least one of the lug sides extends toward the bolt body at an average angle of at least 1°.
6. The bolt assembly of claim 1 , wherein at least one of the lug sides has a first sloped portion defining a first angle and a second sloped portion defining a second angle, wherein the first angle is at least 3° and the second angle is at least 1° with respect to a radius of the bolt extending to a center of the outer lug surface.
7. The bolt assembly of claim 1 , wherein at least one of the opposed lug sides is curved or stepped at an angle that varies between 0° and 90°.
8. The bolt assembly of claim 1 , wherein the aft surface extends toward the bolt body at an average angle from 5° to 20°.
9. The bolt assembly of claim 1 , wherein a radius of curvature of at least one lug side is constant.
10. The bolt assembly of claim 1 , wherein the outer lug surface includes a chamfer.
11. An operating system for a small caliber rifle, the operating system comprising:
a carrier assembly;
a recoil assembly comprising an op-rod of the rifle, the recoil assembly operatively connected to the carrier assembly;
a bolt assembly with a bolt retained by the carrier assembly and having a bolt body with a forward end portion; and
a plurality of lugs extending radially outward from the forward end portion, each of the plurality of lugs having an outer lug surface generally parallel to the major axis of the bolt and having opposed lug sides, an aft surface and an opposed forward surface, the sides and surfaces extending between the outer lug surface and the bolt body,
wherein at least one of the opposed lug sides is arcuate along its length,
wherein the aft surface of the plurality of lugs is arcuate from the outer lug surface to the bolt body,
wherein a connection between the carrier assembly and the recoil assembly is a pivoting interface.
12. The operating system of claim 11 , wherein the pivoting interface is configured to decouple non-axial motion in the recoil assembly from axial motion in the carrier assembly.
13. The operating system of claim 11 , wherein the pivoting interface comprises a recoil assembly rotation slot in a top surface of the carrier assembly, the recoil assembly rotation slot having a concavely-rounded surface configured for rotation therein of a corresponding convexly-rounded extension on the recoil assembly.
14. The operating system of claim 11 , wherein the pivoting interface comprises a rounded interface between the recoil assembly and the carrier assembly, the rounded interface configured to allow free rotation of the recoil assembly with the carrier assembly about a median plane of the small caliber rifle.
15. The operating system of claim 11 , wherein the pivoting interface is configured to direct recoil energy downward and toward an aft end of the small caliber rifle.
16. The operating system of claim 11 , wherein the pivoting interface is configured to reduce at least one of (i) pitch excitation of the carrier assembly, (ii) torque on the carrier assembly, and (iii) moment forces during firing of ammunition.
17. The operating system of claim 11 , wherein the carrier assembly is constructed for maintaining firing pin retention pin in connection with carrier assembly during removal of the bolt.