Bullet forming process
Devices and methods for forming and assembling a bullet in a multi-stage press. In some embodiments, a forward component is radially oversized and forces a jacket outward during a press-fitting stage. In embodiments, the bullet workpiece does not turn over between any stages. In embodiments, one or more stages provide a reduced-diameter stem along with a radial ledge in the die to support the bullet while minimizing potential disturbances to a boat tail region from a punch.
1. A multi-stage process of forming a bullet of a predetermined caliber, the process comprising:
providing a multi-stage die assembly, each stage of the assembly comprising: a stationary die comprising a die cavity extending from a first end to a second end and defining a cavity diameter, a punch configured to press into the first end of the die, and an eject stem defining a stem diameter, the eject stem configured to extend into the second end of the die;
in one or more preliminary stages:
forming a rear component comprising: a core, a jacket comprising a cylindrical jacket body portion extending axially forward of the core, a tapering boat tail shape rearward of the jacket body portion, and a rear face defining a base diameter,
the jacket body portion defining an inner jacket diameter and an outer jacket diameter, the outer jacket diameter being substantially equal to the predetermined caliber of the bullet;
in a loose-fit stage:
placing the rear component in the die with the rear face toward the second end of the die, and
assembling the bullet by inserting a penetrator into the jacket via the punch applying a loose-fit force on the penetrator, the penetrator comprising: a base defining a penetrator diameter sized to press-fit relative to the inner jacket diameter, an ogive portion tapering in diameter from the base, and a forward tip;
in a press-fit stage:
placing the bullet in the die with the rear face toward the second end of the die,
seating the penetrator fully against the core by the punch applying a press-fit force to the penetrator, the press-fit force being greater than the loose-fit force,
radially expanding the jacket in response to the press-fit force, the expanded outer jacket diameter being greater than the predetermined caliber, and
supporting an annulus of the rear face of the rear component against the die, the die of the press-fit stage comprising a ledge extending radially inwardly to engage the annulus of the rear face; and
in a jacket-forming stage:
placing the bullet in the die with the rear face toward the second end of the die,
decreasing the outer jacket diameter via the punch applying a jacket-forming force, and
pressing a forward portion of the jacket against the ogive portion of the penetrator,
in one or more finishing stages:
placing the bullet in the die with the rear face toward the second end of the die, and
the punch applying force to one or more of: the forward tip of the penetrator, the ogive portion of the penetrator, and the forward portion of the jacket,
wherein, in the press-fit stage, the stem diameter is less than the stem diameter in at least one of the loose-fit stage and the jacket-forming stage.
2. The multi-stage process of claim 1 , the penetrator diameter being between about 0.001″-0.002″ more than the inner diameter of the jacket.
3. The multi-stage process of claim 1 , wherein, for every stage of the process, the rear face is placed toward the second end of the die.
4. The multi-stage process of claim 1 , wherein, in the loose-fit stage, the die cavity comprises a characteristic selected from at least one of: being substantially cylindrical or not comprising a tapering diameter corresponding to the boat tail shape of the rear component.
5. The multi-stage process of claim 1 , wherein, in the loose-fit stage, the diameter of the eject stem is substantially equal to the cavity diameter of the die at the rear face of the rear component.
6. The multi-stage process of claim 1 , wherein, in the loose-fit stage, the diameter of the eject stem is greater than the base diameter of the rear face of the rear component.
7. The multi-stage process of claim 1 , wherein, in the press-fit stage, the cavity diameter of the die along the jacket body portion is greater than in either the loose-fit stage or the jacket-forming stage.
8. The multi-stage process of claim 1 , wherein, in the press-fit stage, the die cavity comprises a tapering diameter corresponding to the boat tail shape of the rear component.
9. The multi-stage process of claim 1 , the one or more finishing stages comprising: in an ogive-refining stage after the jacket-forming stage:
placing the bullet in the die with the rear face toward the second end of the die, and
applying an ogive-refining force to one or more of: the forward tip of the penetrator, the ogive portion of the penetrator, and the forward portion of the jacket.
10. The multi-stage process of claim 9 , wherein the ogive-refining force is greater than the jacket-forming force, and wherein, in the ogive-refining stage, the stem diameter is less than the stem diameter in the jacket-forming stage.
11. The multi-stage process of claim 1 , wherein one or more of the loose-fit stage, the press-fit stage, and the jacket-forming stage further comprise:
ejecting the bullet from the die by inserting the eject stem further toward the first end of the die.
12. The multi-stage process of claim 1 , further comprising: in a subsequent stage after the jacket-forming stage, ejecting the bullet from the die by retracting the eject stem.
13. The multi-stage process of claim 1 , wherein the outer jacket diameter is decreased via the punch applying a jacket-forming force based on a predetermined caliber.
14. The multi-stage process of claim 13 , wherein each of the one or more preliminary stages comprise:
placing the rear face of the rear component toward the second end of the die.
15. The multi-stage process of claim 13 , the one or more preliminary stages comprising: in a boat tail forming stage:
placing the rear component in the die with the rear face toward the second end of the die,
the die cavity tapering in diameter toward the second end of the die, and
forming the boat tail shape of the rear component via the punch applying a boat tail forming force to the rear component.
16. The multi-stage process of claim 1 , wherein for one or more stages of the multi-stage die assembly, the die comprises a die insert defining the cavity diameter of the die.
17. The multi-stage process of claim 1 , wherein at least two of the first core component, the jacket, or core comprise a unitary copper component.
18. The multi-stage process of claim 1 , wherein the core comprises a first core component and a second core component.
19. The multi-stage process of claim 1 , wherein the core is formed of a material comprising lead and the jacket is formed of a material comprising copper, and wherein the jacket surrounds the core and defines the rear face of the rear component.
20. A multi-stage die assembly for forming a bullet of a predetermined caliber, the assembly comprising:
three or more stages, each stage comprising:
a stationary die comprising a die cavity extending from a first end to a second end and defining a cavity diameter,
a punch configured to press into the first end of the die, and
an eject stem defining a stem diameter, the eject stem configured to extend into the second end of the die;
individual stages of the three or more stages further comprising:
a loose-fit stage comprising:
the punch comprising a hollow ogive portion configured to engage a forward portion of a bullet workpiece, and
the die comprising the die cavity being substantially cylindrical, the cavity diameter being substantially equal to the predetermined caliber,
a press-fit stage comprising:
the punch comprising a hollow ogive portion configured to engage a forward portion of a bullet workpiece, and
the die comprising:
the die cavity comprising a forward portion proximate the first end and being substantially cylindrical, a boat tail shape portion rearward of the forward portion, and a rear portion proximate the second end and being substantially cylindrical,
a ledge extending radially inwardly from the boat tail shape portion of the die cavity to the rear portion of the die cavity, the ledge configured to engage an annulus of a rear face of a bullet workpiece, and
the cavity diameter along the forward portion of the die cavity being greater than the predetermined caliber, and
a jacket-forming stage comprising:
the punch comprising a hollow ogive shape configured to engage a forward portion of a bullet workpiece,
the die comprising the die cavity being substantially cylindrical, the cavity diameter being substantially equal to the predetermined caliber, and
wherein the stem diameter of the press-fit stage is less than the stem diameter in at least one of the loose-fit stage and the jacket-forming stage.