Projectile launcher

1. A launcher comprising:

an elongated cylindrical body defining a projectile bore having a bore axis;

the body having an open forward exit end;

the body having a gas inlet facility at an opposed rear end;

a movable latch element connected to the body and having a latch portion movable between a retention position in which the latch portion protrudes into the bore and a release position;

the latch element being biased to the retention position such that a projectile in the bore rearward of the latch is retained by the latch portion except until a gas pressure above a selected amount builds up behind the projectile to overcome the biasing of the latch and launch the projectile;

wherein the body defines a latch aperture, and wherein a first portion of the latch resides outside the bore, and the latch portion extends through the latch aperture onto the bore; and

wherein the latch aperture is located at an intermediate position on the body between the exit end and the rear end.

2. The launcher of claim 1 wherein the latch element is clear of the bore when in the release position.

3. The launcher of claim 1 wherein the latch portion protrudes in to the bore by a first amount when in the retention position, and protrudes into the bore by a lesser second amount when in the release position.

4. The launcher of claim 1 wherein the rear of the body is closed except at the gas inlet facility.

5. The launcher of claim 1 wherein the latch portion is proximate the forward exit end of the body.

6. The launcher of claim 1 wherein the latch is a leaf spring.

7. The launcher of claim 1 including a pair of latches.

8. The launcher of claim 7 wherein the latches are diametrically opposite each other on the body.

9. The launcher of claim 1 including a plurality of latches evenly distributed about the body.

10. The launcher of claim 1 including a plurality of latches all positioned at a common position along the length of the body.

11. The launcher of claim 1 wherein the latch portion has a rearward facing cam surface that is offset at a selected angle from a transverse plane perpendicular to the bore axis, such that the latch is responsive to forward force by a projectile to move the latch to the release position.

12. A launcher comprising:

a body defining a projectile bore on a bore axis;

the body having an open forward exit end;

the body having a gas inlet facility at an opposed rear end;

a movable latch element connected to the body and having a latch portion movable between a retention position in which the latch portion protrudes into the bore to a first distance from the bore axis and a release position in which the latch portion is a greater distance from the bore axis;

the latch element being biased to the retention position to retain a projectile in the bore when the projectile is applying a forward force on the latch less than a preselected amount, and to release the projectile when a forward force exceeds the preselected amount;

wherein the body defines a latch aperture, and wherein a first portion of the latch resides outside the bore, and the latch portion extends through the latch aperture onto the bore; and

wherein the latch aperture is located at an intermediate position on the body between the exit end and the rear end.

13. The launcher of claim 12 wherein the rear of the body is closed except at the gas inlet facility.

14. The launcher of claim 12 wherein the latch portion is proximate the forward exit end of the body.

15. The launcher of claim 12 wherein the latch is a leaf spring.

16. The launcher of claim 12 including a pair of latches.

17. The launcher of claim 12 wherein the latch portion has a rearward facing cam surface that is offset at a selected angle from a transverse plane perpendicular to the bore axis, such that the latch is responsive to forward force by a projectile to move the latch to the release position.

18. The launcher of claim 12 wherein the gas inlet facility is a barrel chambered to receive a cartridge.