Here is a description from the Aberdeen Proving Ground ballistic research laboratories:
The pressure variation with time at determined by the gas flow in the barrel.The mass flow through the port is small compared to the mass flow in the barrel itself,and the effect of mass removal is negligible on the pressure history at the port.Thus, the pressure and temperature may be considered prescribed and known, say from an interior ballistics analysis of the weapon.The hot gases expand in the bolt cavity, thereby accelerating the bolt carrier,C.Unlocking of the bolt, D, is accomplished after the carrier has traveled a certain distance, at which distance vent holes are laid free sad the gas in the bolt carrier expands to atmosphere.At this distance the bolt carrier engages the bolt and cartridge, and extraction is accomplished by transferal of energy and momentum of the carrier to the bolt and cartridge.
(The residual momentum and energy of the bolt carrier is sufficient to complete the cycle of cocking the weapon and positioning a new cartridge in the chamber.)
It is the object here to predict for a given pressure and temperature at the port the motion of the bolt carrier referenced in time to the rise of pressure at the port.The motion of the bolt carrier is governed by the pressure and temperature in the bolt carrier cavity.
This is what I have been trying to explain, the buffer-spring weight only controls the bolt carrier velocity(energy) and does not contribute to dwell time..
The pressure variation with time at determined by the gas flow in the barrel.The mass flow through the port is small compared to the mass flow in the barrel itself,and the effect of mass removal is negligible on the pressure history at the port.Thus, the pressure and temperature may be considered prescribed and known, say from an interior ballistics analysis of the weapon.The hot gases expand in the bolt cavity, thereby accelerating the bolt carrier,C.Unlocking of the bolt, D, is accomplished after the carrier has traveled a certain distance, at which distance vent holes are laid free sad the gas in the bolt carrier expands to atmosphere.At this distance the bolt carrier engages the bolt and cartridge, and extraction is accomplished by transferal of energy and momentum of the carrier to the bolt and cartridge.
(The residual momentum and energy of the bolt carrier is sufficient to complete the cycle of cocking the weapon and positioning a new cartridge in the chamber.)
It is the object here to predict for a given pressure and temperature at the port the motion of the bolt carrier referenced in time to the rise of pressure at the port.The motion of the bolt carrier is governed by the pressure and temperature in the bolt carrier cavity.
This is what I have been trying to explain, the buffer-spring weight only controls the bolt carrier velocity(energy) and does not contribute to dwell time..