The single trigger mechanism can either be mechanical, when the switch from one sear to another is a result of the trigger motion, or inertial, when this switch is caused by the motion of an inertia block in response to a counter-recoil of the gun.
The advantage of an inertia block device for the single trigger action is that it can combine two functions: The switch from one sear to another and the disconnect of the trigger from both sears during the time of counter-recoil when the third pull happens.
The trigger is mechanical but has an impressive inertia block
to help prevent doubling.
Propellant gas flowing into the cylinder during firing drives the piston rearward about half an inch, where energy is transferred to a steel inertia block
measuring just over three inches long.
Interceptor sears and independent inertia block
round out the action features.
Larson, I'm pretty sure I know what's causing the misfire on your Browning, likely the inertia block
. I will repair it for $200 and have it to you in the morning as promised."
When the minute hand reaches 60 minutes, a device activated by a central spiral causes the end of the rod to arm a small spring with an inertia block
that, in turn, drives the rotation of the hour disc.
When the shoulder stops the gun, this small inertia block
, which is free to swing back and forth, continues to the rear and pulls the trigger linkage out of contact with the sear from the first barrel.
The forward ends of right- and left-side steel action bars are connected to the inertia block
while their rear ends engage the bolt carrier.
Your shotgun has what's called an inertia block
that shifts under recoil to activate the other hammer for your selected firing sequence.
I tried replacing the inertia blocks
and buffer disc in the stock aluminum buffer with a lead weight, but that did not increase weight much.
So do "inertia blocks
" - reinforced concrete slabs that support heavy air-conditioning systems in large buildings.