Headspace...

[Bruce_in_Oz]

"The extractor claw is disengaged from the rim when the bolt closes."

Good point. You can see the extractor start to pivot outwards as the bolt-handle is locked down. But, as near as I can make out, it never deflects far enough to be completely clear of the outer diameter of the rim. Again, this ties in with the whole beauty of the helical locking system on these rifles.

As the bolt handle is raised, because the bolt-head thread is a coarse right-hand thread, the bolt head only moves back a little, initially, until the "little" lug on the bolt body picks up the 1: 1inch unlocking cam surface and starts the primary extraction process properly.

Clever things, these old rifles.

Information

Warning: This is a relatively older thread This discussion is older than 360 days. Some information contained in it may no longer be current.

[Son]

"The extractor claw is disengaged from the rim when the bolt closes."

Good point. You can see the extractor start to pivot outwards as the bolt-handle is locked down. But, as near as I can make out, it never deflects far enough to be completely clear of the outer diameter of the rim. Again, this ties in with the whole beauty of the helical locking system on these rifles.

As the bolt handle is raised, because the bolt-head thread is a coarse right-hand thread, the bolt head only moves back a little, initially, until the "little" lug on the bolt body picks up the 1: 1inch unlocking cam surface and starts the primary extraction process properly.

Clever things, these old rifles.

Couldn't agree more. The design features that made this action so good and saw it through such a long service life are taken for granted by so many- because they just work so good.

I did a few pics a while back demonstrating primary extraction too. The bolt head is screwing forward as the handle is lifted, but the camming action of the lugs while unlocking still brings the bolt face back enough to break the grip of the chamber on the case. The mechanical advantage is huge! Over two inches of travel on the bolt knob giving so little rearward movement of the extractor.
I had to try to explain why a case should not be still stuck in the chamber once the bolt handle was lifted. Sometimes it takes a lot of work to change the things people have set in their heads...

I'll stick all the pics up shortly.

Ok.. back to my earlier post, here are three pics, first showing the dial indicator on the extractor claw, the bolt almost closed just at the point where the curved surface to the inside of the claw meets the curve bottomed angled recess in the back of the barrel.
Second pic shows the bolt closed and the claw has come away from the base pf the cartridge by almost .1 mm.
Third pic is of the back of the barrel where the recess for the extractor is and the bolt just starting to be withdrawn, viewed the side through the cut out in the receiver ring.

Attachment 84272

Attachment 84271

Attachment 84273

Next up, pic one shows the bolt closed. Dial indicator on the back of the bolt head.
Second pic has the bolt handle just lifted a bit and the dial indicator is reading .11 mm. Only a very small movement for the inch or so of lift on the bolt handle. This is where the mechanical advantage makes it so easy to break the grip of the case from the chamber.
Pic three shows the bolt up completely unlocked and ready to be drawn rearward to complete extraction and eject the spent case. Note, there has been no more rearward movement of the bolt head from the previous pic meaning that primary extraction should take place in the first half of bolt lift.

Attachment 84275

Attachment 84276

Attachment 84277