The Charlton has some design features that would seem to be unique.
The gas port is within a gas block, just like most all other gas operated designs. But the piston does not extend up to the gas block. Instead, there is a tube extending rearwards, to bring the gas back to the piston and its cylinder. The piston itself is quite short. Also note that the camming system on the bolt does not incorporate any provision for rearward movement of the slide prior to the cam starting to open the bolt. I suspect that the combination of these features is related to achieving the necessary dwell time, to keep the breech closed until pressures are dropping.
Usually the recoil spring is behind the reciprocating parts. In the Charlton, it is inside the second tube parallel to the barrel. A rod extends through it. When the breech opens, the rod pulls back on the front end of the recoil spring, compressing it.
The adaptation of the original trigger parts is interesting. A disconnect function is included, of course. In an autoloading design, there must be a provision to prevent fire until the breech is closed and locked. In the Charlton, there is a vertical plunger, which protrudes vertically just in front of the right hand locking abutment. As the bolt rotates to lock, the rear of the locking lug presses this plunger downwards.
The cylindrical assembly at the rear of the receiver extension is a buffer. In the manually operated rifle, rearward movement of the Lee Enfield bolt is stopped by the bolthead striking the receiver's locking abutment. The buffer would serve to reduce violent hammering of the bolthead against this abutment in auto fire.
The short, slick movement of the Lee Enfield's bolt action likely contributed to the Charlton being functional.
The gas port is within a gas block, just like most all other gas operated designs. But the piston does not extend up to the gas block. Instead, there is a tube extending rearwards, to bring the gas back to the piston and its cylinder. The piston itself is quite short. Also note that the camming system on the bolt does not incorporate any provision for rearward movement of the slide prior to the cam starting to open the bolt. I suspect that the combination of these features is related to achieving the necessary dwell time, to keep the breech closed until pressures are dropping.
Usually the recoil spring is behind the reciprocating parts. In the Charlton, it is inside the second tube parallel to the barrel. A rod extends through it. When the breech opens, the rod pulls back on the front end of the recoil spring, compressing it.
The adaptation of the original trigger parts is interesting. A disconnect function is included, of course. In an autoloading design, there must be a provision to prevent fire until the breech is closed and locked. In the Charlton, there is a vertical plunger, which protrudes vertically just in front of the right hand locking abutment. As the bolt rotates to lock, the rear of the locking lug presses this plunger downwards.
The cylindrical assembly at the rear of the receiver extension is a buffer. In the manually operated rifle, rearward movement of the Lee Enfield bolt is stopped by the bolthead striking the receiver's locking abutment. The buffer would serve to reduce violent hammering of the bolthead against this abutment in auto fire.
The short, slick movement of the Lee Enfield's bolt action likely contributed to the Charlton being functional.
