To disassemble, grip the bolt assembly as shown above. While pushing forward on the bolt handle and pulling rearward on the cocking piece, rotate the cocking piece counter-clockwise 90 degrees.
Using a block of wood, press the firing pin against the wood with downward pressure on the bolt handle. While maintaining firm pressure downward, unscrew the cocking piece counter-clockwise until it unscrews from the firing pin.
In order to install the bolt head onto the firing pin the flat side of the firing pin must be in alignment with the bolt as shown. If it is not, use a tool and rotate the firing pin until it aligns with the bolt as shown above.
To connect the bolt head with the connecting bar, align the connecting bar lug with the bolt head channel. Slide the bolt head onto the connecting bar and rotate the bolt head clockwise until it stops.
The next step is to verify the firing pin protrusion is properly adjusted. Failure to ensure the firing pin is adjusted could result in misfires (due to the pin being too short) or worse, a punctured primer with potential for catastrophic failure. Shown above is the Mosin Nagant bolt adjustment tool.
Using the bolt tool, slide the .075 gauge over the firing pin. If the firing pin passes through the gauge the pin is too short and needs to be adjust with the cocking piece. To do so, remove the bolt head and connecting bar and screw the bolt head 1/2 to one full turn. Reassemble and measure again. If the firing pin does not pass through the gauge it is set to a proper minimum length.
Once the firing pin passes the .075″ gauge, test the firing pin on the .095″ gauge. If the firing pin does not pass through the gauge it is too long and needs to be adjusted. To do so, remove the bolt head and connecting bar and unscrew the bolt head 1/2 to one full turn. Reassemble and measure again. If the firing pin passes through the gauge it is set to maximum allowable length.
Once the firing pin has been properly adjusted we need only to simply re-cock the bolt. Using the hand position above, push forward on the bolt handle and pull rearward on the cocking and rotate the cocking piece 90 degrees and release.
Here’s a quick video showing how uncomplicated it can be with practice.