Hello gents -
I am working to wrap my brain around the concept of dwell time. Can anyone share some information on this matter?
My understanding of it is not yet complete…
thanks!
Dwell Time:
The time from when the projectile passes the gas port until it exits the muzzle.
Keep in mind, Dwell Time is but one factor in a complicated system of interrelated factors.
IMO, it isnt even the most important factor.
See here for a little further explanation:
https://www.m4carbine.net/showthread.php?173315-11-5�-Mid-Length-Barrel-Discussion
As above. Dwell time is the only point in the firing cycle where the gas system is being charged. As soon as the bullet leaves the barrel, the system begins discharging.
It’s not always that simple, dwell time, for good or bad is mostly associated in AR type guns as the distance from the port to the muzzle.
Dwell time really is just a measurement of time for an event. This event could be the measurement in time that the gas port is exposed to operating barrel pressure to cycle the action, like many assume in a AR barrel. The term could be used correctly to describe other events in the AR platform. Someone speaking of the dwell time of an AR carrier to exhaust gas before disengaging the key interface, or speaking of it in terms of the magazine catching up during carrier over travel, or disconnect engagement times for the trigger, or carrier caming before unlocking is initiated, or etc, etc…They may also use the term correctly in those cases, but good or bad, most associate the term in AR type guns to a measurement in length between the gas port and the muzzle. At some point in informing consumers about products, there was something that happened that made a more complicated series of events more palatable to users to simply say dwell time is measured in inches from the port to the muzzle instead of saying what it really was or what it could mean in a function of time.
Don’t forget the blowdown time.
The muzzle pressure on a 20" barrel is ~12kpsi.
It takes 2-3 ms to blowdown to <1kpsi.
Carrier venting occurs a little less than 2ms after bullet exit and extraction occurs a little after 2ms.
The pressure event in the bolt carrier is effectively done after 3ms.