Folding stock

1. A stock for a firearm, comprising:

a distal portion for interfacing with a firearm, the distal portion comprising one of a lock catch or a lock and one of a detent or a detent notch distinct from the one of a lock catch or a lock; and

a proximal portion, the proximal portion comprising the other one of a lock catch or a lock and the other one of a detent or a detent notch; wherein

the stock comprises a folded configuration and an unfolded configuration;

the lock is shaped to engage the lock catch in response to an unfolding moment to selectively maintain the stock in the unfolded configuration;

the detent is shaped to engage the detent notch to selectively maintain the stock in the folded configuration; and

the lock comprises a safe-release mechanism to allow the folding stock to move into the folded configuration from the unfolded configuration when a folding moment is applied to the stock when the lock is engaged with the lock catch, the folding moment at least an order of magnitude greater than the unfolding moment.

2. The stock of claim 1 , wherein:

the detent is a spring-biased translational detent;

and the lock is a spring-biased button shaped to travel in a direction different from a direction of travel of the detent.

3. The stock of claim 2 , wherein:

the button engages the lock catch when the stock is in the unfolded configuration; and

the button is shaped to disengage from the lock catch when the button is compressed into the proximal portion.

4. The stock of claim 3 , wherein:

the button is spring-biased towards the extended position, and comprises an angled surface to engage an angled lock catch surface of the lock catch, whereby the button is shaped to auto-disengage from the lock catch when the stock is forcibly moved from the unfolded configuration.

5. The stock of claim 1 , wherein:

the safe-release mechanism has a first lock catch engagement surface and a second lock catch engagement surface; and

the first lock catch engagement surface is shaped to cause the lock to compress as the stock is moved into the unfolded configuration, the first lock catch engagement surface having an angle further shaped to cause the lock to compress under a first force;

the second lock catch engagement surface is shaped to cause the lock to compress as the stock is moved from the unfolded configuration into the folded configuration, the second lock catch engagement surface having an angle further shaped to cause the lock to compress under a second force, the second force greater than the first force.

6. The stock of claim 1 , wherein:

the distal portion comprises a longitudinal axis and a vertical axis;

the proximal portion is rotatably coupled to the distal portion;

the proximal portion configured to rotate about an axis that is tilted no more than 5 degrees relative to the vertical axis.

7. The stock of claim 1 , wherein:

the detent and the detent catch are shaped to provide resistance to unfolding.

8. The stock of claim 1 , further comprising:

a cheek riser removably attached to the proximal portion, the cheek riser comprising a charging handle glance surface, the glance surface angled relative to at least one of a longitudinal axis or a vertical axis of the proximal portion.

9. The stock of claim 1 , wherein the proximal portion further comprises:

a length of pull adjustment mechanism having a lever and a length of pull adjustment rail, the lever shaped to selectively engage the length of pull adjustment rail at any one of a plurality of adjustment recesses in the length of pull adjustment rail.

10. The stock of claim 9 , wherein:

the lever is shaped to disengage from the length of pull adjustment rail in response to a longitudinal force on the lever.

11. The stock of claim 10 , wherein:

the longitudinal force causes the lever to rotate about a transverse hinge, whereby the lever is disengaged from the length of pull adjustment rail.

12. The stock of claim 1 , wherein:

the distal portion comprises a modifiable firearm mount having a primary mount body, a modifier body, and a fastener;

the primary mount body and the modifier body are shaped to fit within a recess of a receiver of a firearm; and

the fastener adjustably and operatively couples the modifier body to the primary mount body to adjust a maximum insert profile.

13. The stock of claim 12 , wherein:

the fastener further couples a quick detach mount to the primary mount body.

14. The stock of claim 12 , wherein:

the primary mount body comprises an angled distal surface; and

the modifier body comprises an angled proximal surface shaped to translate across the angled distal surface between a retracted position and an extended position relative to the primary mount body; and wherein

the maximum insert profile is defined by the primary mount body when the modifier body is in the retracted position; and

the maximum insert profile is defined by the primary mount body and the modifier body when the modifier body is in the extended position.

15. A method of using a stock for a firearm, the method comprising:

applying an unfolding moment to a folding stock to move the folding stock from a folded configuration to an unfolded configuration;

causing a detent to engage a detent notch to selectively maintain the folding stock in the folded configuration; and

causing a lock to engage a lock catch to selectively maintain the folding stock in the unfolded configuration, the lock and the lock catch distinct from the detent and the detent catch, the lock having a safe-release mechanism to allow the folding stock to move into the folded configuration from the unfolded configuration when a folding moment is applied to the folding stock when the lock is engaged with the lock catch; and

applying a folding moment to the folding stock to move the folding stock into the folded configuration from the unfolded configuration without disengaging the lock from the lock catch, the folding moment at least an order of magnitude greater than the unfolding moment.

16. The method of claim 15 , further comprising:

disengaging the lock from the lock catch by compressing the lock.

17. The method of claim 15 , further comprising:

disengaging the detent from the detent catch by applying an unfolding moment to move the stock from a folded configuration to an unfolded configuration.

18. The method of claim 15 , wherein:

the applying the folding moment and the applying the unfolding moment comprise rotating a proximal portion of the stock relative to a distal portion of the stock about a hinge axis without translating the proximal portion along the hinge axis; and wherein

the hinge axis is tilted no more than 5 degrees from an axis that is vertical relative to a longitudinal axis of the distal portion.