PNWTargets Wrote:BCG dwell is when the BCG moves from static (back/forward). Spring pressure does affect this dynamic movement. When the BCG is still static as gas flows to it, that has to do with holding gas pressure. Possibly I am not explaining what I mean clearly.
The dwell time is the length of time the gas system is charged, period.
Bolt cam tract length (lock time).
Pressure curve (powder or bullet type)
Barrel port size (amount of pressure)
Bolt carrier resistance (force needed to move the carrier and bolt to cycle)
Timing of these variables are critical to function..Make changes to any of these variables and malfunctions can occur..
Moving the location of the barrel gas port will change the dwell time ( the amount of time the gas system is pressurized).
Change the spring-buffer-carrier weight, will change the cycle resistance to gas pressure..
Change the bolt cam tract and lock time changes..
Change the powder or bullet type and the pressure curve changes..
Open or shrink the gas port and the amount of pressure changes..
This is why they discovered the new buffer's added weight on the dwell time or bolt opening cycle was (negligible)..What it did do was slow the cycle rate (bolt carrier velocity) and prevented bolt bounce..
This is why locating the gas port farther from the muzzle will result in a longer dwell time and a gas port near the muzzle will have a shorter dwell time.
Adjustments are made all the time to the AR function with the gas system by opening or shrinking gas ports, gas port locations, buffer springs, weights and carriers and even different bolt cam tact time length..
When the bullet passes the gas port the system is charged, even in the bolt carrier. The Stoner internal piston will actually push the bolt forward while the system is charged away from the locking lugs in the barrel extension, relieving stress on the bolt, while simultaneously pushing the carrier the opposite direction . The bolt will not unlock or the carrier cycle until the port pressure has dropped after the bullet has left the barrel..The residual pressure in the system cycles the bolt carrier..The heavier the buffer, the slower the bolt carrier cycle (velocity) occurs. The lighter the buffer, the faster the carrier cycles (velocity) occurs..The dwell time is the time the system is charged..
A good example of dwell time is an air hose. If you have one length of hose and charge it with 120 lbs of air the system is charged with 120lbs. Disconnect the hose and the residual air escapes. Now hook up 3 lengths of the same hose and do the same. It will take a longer time to expel the residual air, even though it also has the same 120lbs of air. That is dwell time..