Ruger M77 MkII Bolt Disassembly?

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May 28, 2003
I have my Ruger M77 MkII rifle bolt "partially" diassembled, but now it won't go further or go back. The Owner's Manual is worse than useless - it's misleading - so I could use some help.

The manul refers to something they call the "disassembly hole," but they don't describe it either by size or location. (An online search after the fact indicated it's probably about paperclip diameter and is on the cocking piece.) The manual then says to unscrew the cocking piece, but I can't see how that is possible with the underbolt cocking-piece lug extension blocking a counter-clockwise unscrewing attempt.

First things first: is the disassembly hole the one that's horizontal or vertical, or in other words, next to the underbolt cocking-piece lug or is it the one that's through that lug? Or is it some other hole entirely?

Next, picking the wrong disassembly hole (further forward on the bolt), I began to unscrew the cocked firing pin assembly, but it only went halfway before butting up against the bolt body. At this point, I'd settle for getting the cocker back up to the fully-cocked resting position.

Thanks for any help.

I have not taken down a Mk II, but bear with me and maybe I can help.

Look at the bottom of the bolt sleeve, which is the part you are trying to unscrew. You should see the cocking piece sticking down. That is the part that sits on the sear until the trigger is pulled, then goes forward. It is attached to the firing pin.

Now, hold the front edge of the cocking piece against a block of wood (edge of workbench if it is sharp) and push forward on the bolt. This will move the cocking piece back out of the bolt sleeve until the small hole in the bottom of the cocking piece is exposed.

Insert a wire, punch, or paper clip of appropriate size through that hole.

The cocking piece should now stay back and you can unscrew the bolt sleeve. Once the bolt is reassembled, you should be able to do the same thing to remove whatever is in the hole and let the bolt be reinserted in the rifle.

I don't recommend any further disasembly. Do not drive out the pin that holds the firing pin to the cocking piece. If you do that, you are on your own and good luck.

Thanks, Jim, I appreciate your help. Ruger's instructions were ...inadequate.

The disassembly hole is, of course, in the cocking piece - thank you. It would have been nice for the Users Manual not to assume I knew this.

The bolt was not, as I stated, "partially disassembled." That was another misunderstanding of mine drawn from the manual. The proper approach for me would have been to insert a tool - a pin - into the disassembly hole to torque the entire module from the bolt proper. I didn't gain that understanding from the manual, however - I twisted a smaller section of the workings and merely disengaged the cocking piece from its detent and couldn't move it either direction after that.

In any case, a frozen bolt has now been disassembled and fixed.

The reason for the frozen bolt, and the reason for the need to disassemble it, was a pierced primer. As I suspected, the pierced primer blowback flowed back past the firing pin, then when the firing pin returned to rest, froze into position from the now-solidified gaseous copper and carbon. With that cleaned out, the bolt functions properly again. I really don't care for the human-engineering, or lack of it, that Ruger used in design for maintenance. I'd prefer to be able to take down the bolt without tools, as on a Winchester Model 70.

OTOH, it's hard to fault the gas-handling capability of the M77. I did not experience any gas to the face in my minor KB - that counts for something. I also learned not to put off trimming or annealing cases "for just one more firing." Lesson's learned, and I lived through it.

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