Handling my new TOZ 78 .22LR bolt action rifle in preparation for the first day at the range with it, I noticed a problem – the firing pin was jamming up and the rifle would not fire. Dry firing it would either result in nothing at all, or a small click, with the firing pin moving forward slightly, but not enough to strike the rim of the cartridge. The rear of the firing pin (which protrudes when cocked, and sits flush when uncocked (i.e. after it has fired) was still protruding. Removing the bolt from the rifle and cocking by hand, the firing pin would release partially once or twice, but after that would not release at all.
Here’s the exploded view of the bolt from the manual
Here is the bolt, freshly assembled and uncocked. Note the position of the bushing, the edge of which is just visible under the cap, back from the hammer.
Inside the cap, there is a pin, this lines up with a slot in the bolt handle, and protrudes through this slot and mates with the top of the bushing. On cocking, the hammer pushes the firing pin back. The spring pushes against the bushing, which is held in place by the pin inside the cap. This spring pressure is what propels the firing pin forward to strike the primer.
Here’s a picture of the bolt cocked, but jammed. Note that the hammer is off the ramp, but not forward as it should be. Note also that the bushing is no longer visible
What happened was that the pin within the cap was not protruding sufficiently inside the cap, which meant it did not properly engage the bushing. Instead, the bushing was slipping “under” the pin and jamming. This meant there was not adequate spring pressure to drive the firing pin forwards. The busing was stuck in place, and the firing pin/hammer were able to be manipulated forwards or backwards, with no spring pressure to resist movement.
The pin is a simple press fit. There is a hole in the side of the cap’s ridge where the pin protrudes – looks like it might be a grub screw but it isn’t. Perhaps maybe there is supposed to be a locking rivet there, or the pin is supposed to be punched to hold it in place? Unsure. I was able to gently tap the pin from the outside to push it through sufficient to engage the bushing. Whether or not this will move in time I do not know – if so I may need to look at a locking mechanism – loctite 282, or perhaps punching the side to deform the pin enough to prevent movement.
Photo below shows before it was fixed. Note how the pin protrudes on the outside of the cap. Once fixed, it sits flush.