Gas operated weapon

摘要

Improvements in, or related to gas operated automatic or semi-automatic weapons. A gas operated firearm having a receiver 1 including a rear wall 100 at one end and a barrel 10 at the other, with a bolt carrier assembly 3 that moves reciprocally within the aforesaid receiver is arranged to co-operate with a main drive spring 307 that urges the bolt carrier assembly towards the barrel. The weapon is designed so that in one aspect of the invention on an automatic cocking cycle the bolt overtravels the cartridge feed point by a distance equal to or greater than the overall length of a live cartridge. In a further aspect, the gun is additionally designed using parameters calculated such that a substantially constant reaction is felt by a user. The parameters used here are essentially the product of sprung weight (the total weight in kg of all the components driven by the main spring) x the spring force (an average value of spring force that accelerates and retards the sprung weight) x cycling distance (the length of allowable travel of the bolt carrier assembly in metres) which is equal to (0.51)2 x 0.5g +-15% where I is the cartridge impulse and g is the acceleration due to gravity. The length of allowable travel of the bolt carrier assembly is arranged such that the assembly does not impact on a positive stop (100).