07-12-2017, 10:36 PM
LRRPF52 Wrote:See the chamber formed by the gas ring flange and the carrier. When the gas rapidly fills that area, it starts pushing outwards against the rear of the bolt and the carrier wall that the bolt tail protrudes through.
That's what starts inertia in the Stoner gas system, whereas on a Ljungman, there is a gas pocket above the carrier where the gas pushes against, causing the carrier to move rearward.
The carrier key on the AR15 is just a path for the gas to travel through until it hits the expansion chamber. Once sufficient inertia has been generated, the carrier moves such that the vent holes will pass over the gas rings, and allow any excess gas pressure to vent out of the ejection port. This is another reason why the AR15 is so debris tolerant, as this gas will blow mud and dirt away from the action upon firing.
An adjustable gas key chokes the amount of gas that can enter the expansion chamber within the timing of gas expansion from the system.
Most adjustable gas blocks choke the gas port under the gas block right above the port on the barrel.
I think I'm getting there - sometimes you remind me of my mechanic talking about the diesel engines in my busses - I follow and then ...... whoosh! Over my head
.If I have an adjustable gas block and am at the point where I am just reliably cycling, dialing down an adjustable gas key should enable me slow my bolt down and delay rotation and hence, hopefully stop the extractor from ripping at the rim before the case relaxes. But would that have the effect of dialing down the gas block and impact cycling? Or would it delay the cycling and still provide sufficient force to cycle?