Abstract: A recoil brake includes a control rod disposed in a central opening in a piston and cylinder assembly. A fluid passage leads from the piston to the control rod. A long stroke body is fixed to the piston and defines a long stroke orifice around the control rod. A short stroke body is removably disposed in the long stroke orifice. The short stroke body defines a short stroke orifice around the control rod, the short stroke orifice being smaller than the long stroke orifice. The recoil brake may be used with a 120 mm gun.

Abstract: An obturator for guarding the primary sealing surfaces of a step wedge brhblock gun from post-firing residue buildup assures greater survivability of the obturator without the necessity of cleaning after each firing. The device includes an active tube insert for facilitating face seal force multiplication, out of bore lip and face seals, an inbore piston polymer with expanding residue guard, and an out of bore face seal with a residue-tolerant polymer.

Abstract: A device that locks a threaded collar around a cylindrical gun barrel has a lunger extending in a radial direction through the collar. The plunger rides upon a series of ratchet teeth, disposed around the circumference of the gun barrel. The ratchet teeth include ramps and steps. As the collar is threaded onto the gun barrel, the plunger rides up the ramp of each ratchet tooth and drops into the step of the next ratchet tooth around the gun barrel. When in place, the plunger is pushed backwards against the wall of the ratchet tooth and arrests rotation of the collar in the unthreading direction. To remove the collar, the plunger is lifted clear of the ratchet tooth. With the plunger held clear of the step of the ratchet tooth, the threaded collar can be unthreaded.

Abstract: A split wedge/breechblock for inserting and extracting the bridge seal from he powder chamber of a gun tube. The device includes a sealing mechanism for the sliding surfaces between the wedge and the breechblock, a bridge seal for use in the XM 297 gun system, and an improved stepped wedge and breechblock design which eliminates adverse downward forces during gun firing.