Sight assembly and system with firearm status indicator

1. A system of determining a number of rounds in a firearm magazine, the system comprising:

a firearm defining a magazine well;

Hall-effect sensors arranged in the magazine well, individual Hall-effect sensors having a unique combination of a vertical position and a horizontal position, wherein each unique combination is representative of a number of rounds;

a magazine sized and configured to be seated in the magazine well, the magazine including a follower retained in and movable along an inside of a magazine tube; and

at least one magnet in or on the follower, the at least one magnet arranged to align with a single one of the Hall-effect sensors, in use, to identify a quantity of ammunition in the magazine when the magazine is seated in the magazine well.

2. The system of claim 1 , wherein the firearm is configured as a semiautomatic handgun with a polymeric handgun grip module.

3. The system of claim 1 , wherein the firearm includes a lower receiver and an upper receiver.

4. The system of claim 1 , wherein each of the Hall-effect sensors is arranged in one of at least four columns and in one of at least 10 rows.

5. The system of claim 4 , wherein the at least 10 rows includes at least 20 rows.

6. The system of claim 1 , further comprising a sight assembly mounted on the firearm, wherein the Hall-effect sensors are disposed in communication with the sight assembly and wherein the sight assembly is configured to display a round count to a user based on communication with one or more of the Hall-effect sensors when the magazine is seated in the magazine well.

7. The system of claim 6 , wherein the sight assembly comprises an optical sight.

8. The system of claim 7 , wherein the optical sight is configured as a reflex sight.

9. The system of claim 1 , wherein the at least one magnet includes two or more magnets arranged horizontally on the follower.

10. A system for determining a number of rounds in a firearm magazine, the system comprising:

a firearm defining a magazine well;

sensors arranged in the magazine well in a grid defined by rows and columns, individual rows having a sensor in one or more of at least four row positions and individual columns having sensors in three or more of at least 10 column positions, wherein the one or more sensors in each row define a number of rounds in a magazine seated in the magazine well;

a magazine sized and configured to be seated in the magazine well, the magazine including a follower retained in and movable among vertical positions along an inside of a magazine tube, wherein the magazine tube defines openings corresponding to the sensors when the magazine is seated in the magazine well;

reflective material on the follower, wherein for each of the vertical positions of the follower the reflective material aligns via the openings with the sensor in each of the one or more row positions, thereby identifying the number of rounds contained in the magazine when the magazine is seated in the magazine well; and

a display on the firearm, the display disposed in communication with the sensors and configured to display the number of rounds contained in the magazine seated in the magazine well.

11. The system of claim 10 , wherein the firearm is configured as a semiautomatic handgun with a handgun grip module.

12. The system of claim 10 , wherein the firearm includes a lower receiver and an upper receiver.

13. The system of claim 10 , wherein the grid includes at least 20 rows.

14. The system of claim 10 , wherein the display comprises an optical sight on the firearm.

15. The system of claim 14 , wherein the optical sight is configured as a reflex sight.

16. The system of claim 10 , wherein the sensors are configured as optical sensors.

17. The system of claim 10 , wherein at least some of the rows contain two or more sensors.

18. The system of claim 10 , wherein each of the rows contains a single sensor.

19. The system of claim 10 , wherein the openings are defined in a rear wall of the magazine tube.