Type 99 Bolt Assembly

[Tkaxman]

Does anyone know how to unassemble the bolt after it has been assembled in the wrong position in order to make the bolt inoperable?

Currently the large round "knob" at the back of the bolt has a knob that hits the receiver frame so the bolt cannot be cycled. I believe they used to do this for safety reasons when shipping the guns back to the states? Apparently there is a way to "jump" the knob back into the correct position, so the bolt can function normally. This gun has been handed down through the family, and is in great condition...mum intact!
Thanks for any input!

Information

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[gsimmons]

The "knob" is the safety.By pushing in and turning ( don't remember which way) it should turn off safety.

[Tkaxman]

Yes, I can push the knob in, but it was assembled 90 degrees off, making it impossible to turn the safety off.
There is a small extension on the knob that hits the receiver frame....I can only move it 1/8 of an inch or so.

[jmoore]

I didn't think it was possible to assemble a Japanese T38/99 bolt incorrectly! I can't do it.

 

Mmmmm, is the firing pin in the cocking notch or is it all the way forward? If it's decocked you just need to draw the sear engagagement protrusion on the rear of the firing pin rearward and engage it in the cocking notch. It's easiest to do if the bolt is removed from the rifle. (The firing pin tail should then be in line w/ the safety tab and 180 degrees opposite the bolt handle.) That will free up the safety for removal and/or normal function, unless there's something REALLY odd going on!

[Patrick Chadwick]

Jmoore is 100% right.

Does anyone know how to unassemble the bolt after it has been assembled in the wrong position in order to make the bolt inoperable?

It was not intended to make the bolt inoperable, but to relax the spring for storage. The bolt is a cock-on-opening type, so if (like me) you store the bolt outside the rifle - to save space in the gun cabinet - the spring will be permanently compressed, and eventually weaken. So the compression is relaxed by moving the cocking piece out of the notch and rotating it, thereby allowing the cocking piece to slide forwards into the "fired" position. In this position the safety cap cannot be rotated, as Tkaxman has correctly observed. And so, to use the bolt again or dismantle it, the procedure is reversed, as described by jmoore.

BTW I think the Arisaka bolt is a brilliant improvement on the normal Mauser type, for reduction in parts and ease of dismantling, without needing three strong hands, blocks of hardwood, and safety glasses for protection against flying springs!

Patrick.

[Tkaxman]

Thanks All!
I'll try it tonight when I get home from work. If I still have issues, I'll try to upload some picures.
I appreciate the help!

[Milsurp Collector]

The bolt is a cock-on-opening type, so if (like me) you store the bolt outside the rifle - to save space in the gun cabinet - the spring will be permanently compressed, and eventually weaken.

Constant compression does not weaken springs, that is a common misconception.
Magazine spring madness: | American Handgunner | Find Articles at BNET

Cyclic loading is what weakens springs, not static compression. Compressing and relaxing the spring (by cocking and decocking) will wear a spring out faster than leaving it compressed (cocked).

[Tkaxman]

Tried it and still dont really know what i need to do. Can you explain it any simpler?

[Patrick Chadwick]

I think this is one of those cases where a picture is worth a thousand words.
So here are the pics:
This is how your bolt should appear.

Attachment 16885

Note that the cocking piece ledge (the lug shining brightly at the bottom) is 180 degress opposite the bolt handle. To clarify that, here is a closeup:

Attachment 16882

Note that the cocking piece is held safely back by sitting in a small notch. This means that the firing spring is compressed. If you look at the rifle, it will be clear that it is ONLY possible to insert the bolt if the ledge is in this position.

However, jmoore and I are guessing that your bolt looks like this:

Attachment 16884

In this position, the cocking piece has moved right forwards into the large notch. This is the position it takes up AFTER firing. So the firing spring has been relaxed, which is why cock-on-opening bolts are stored like this. BUT in this position you cannot move the safety. I.e. the safety only works on a cocked bolt.

You now need to use a piece of hardwood, brass or similar (I used an insulated screwdriver) but NOT blank steel (to avoid damaging the clean edge of the cocking piece ledge!) to push the cocking piece back

Attachment 16883

and turn it 1/4 turn clockwise, so that it is sitting in the small notch again, and the complete assembly appears as in the first two pics.

So it now looks this

Attachment 16882

You will then find that
1) you can insert the bolt into the rifle, as intended.
2) by pushing in the safety knob and turning it 1/4 turn clockwise, the whole assembly comes apart, without requiring great strength, jigs etc. - a brilliant construction

Attachment 16881

And to reassemble, put it all together, push on the safety cap (it will ONLY go on in one position) and turn it 1/4 turn anti-clockwise.

I am wary of using the term foolproof, but the Arisaka bolt is a pretty good approximation to that state. If this doesn't work, something horrible has been done to your rifle, and you will need to post some photos.

Eagerly awaiting news of your success!

Patrick

[jmoore]

Mr. Chadwick gets a HUGE thanks from me for his in-depth answer. There's a 500% bonus in his next "Forum Guru" paycheck as well...

(Tkaxman, if this doesn't sort the drama you will either need to post pictures or seek the services of a GOOD gunsmith!)