Mosin Nagant Bolt Disassembly & Reassembly

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The Mosin Nagant Rifle Bolt

Disassembly

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.

Pull the bolt head and connecting bar forward and off the bolt assembly.

Rotate the bolt head clockwise as far as it will go and slide it off the connecting bar.

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.

Remove the firing pin and firing pin spring from the bolt body.

Remove the firing pin spring from the firing pin.

Disassembly of the bolt is complete.

Bolt Reassembly

Replace the firing pin spring onto the firing pin.

Insert the firing pin and firing pin spring into the bolt body.

Using a wood block, press the firing pin against the wood by pushing down on the bolt handle compressing the firing pin spring completely.

While keeping the firing pin spring compressed, thread the cocking piece onto the threaded end of the firing pin until the firing pin is flush with the cocking piece.

Ensure the cocking piece is in this position once you’ve screwed it on to the firing pin.

The cuts in the cocking piece should align relatively close with the cut in the end of 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 bolt head and connecting bar should appear as shown above.

Slide the bolt head and connecting bar onto the firing pin.

While sliding the connecting bar onto the firing pin, align the bolt head lug with the bolt body channel.

Allow the bolt head lug to slide into the body channel as shown above.

…and at the same time, ensure the cocking piece lug slides into the channel of the connecting bar at the opposite end.

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.

The second and third notches are calibrated to measure the firing pin protrusion.  The firing pin protrusion must measure between .075 and .095 inches.

To measure the firing pin protrusion, ensure the firing pin is fully exposed out of the bolt face.

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.

Bolt assembly is complete.

Here’s a quick video showing how uncomplicated it can be with practice.

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