Patent ID: 7971517

Claim:
A gun, comprising: a barrel defining a barrel axis and having an external barrel surface about the perimeter of the barrel, the external barrel surface including a collar section extending along a length of the barrel; a cradle having a cradle bore for accommodating a section of the barrel wherein the barrel is slidably mounted in the cradle bore such that the barrel can move relative to the cradle along the barrel axis across a range of barrel positions; and an interface having a polygonal cross-section, the interface being defined by the slidable contact between the collar section of the external barrel surface and the cradle, wherein the interface: i) prevents rotation of the barrel relative to the cradle about the barrel axis; ii) is maintained at a section of the cradle over the entire range of barrel positions; iii) provides slidable contact at all points of the interface; and iv) is maintained over the entire range of barrel positions.