doublegunshop.com - home Forums General Discussion Classic & Custom Single Barreled Sporting Rifles @ doublegunshop.com More Old Time Gunsmithing - Mauser Bolts

Helo Guys

Recently I had a 98 bolt shortened to fit a Model B Kurz sporting action. The work was carried out by a reputable smith who has done excellent work for me in the past, including new bolt handles, as good as any I've seen. His approach to shorten the bolt was to cut the bolt between the rear lug and guide rib, and tig weld it. He had to re-harden the cocking cam.

I am currently discussing the result with him as although the bolt functions, it is not "slick" and appears to have the slighest bend/bow in it. The bow is apparent more by eye than measurement, a straight edge does show some waviness but nothing definitive.

I now want to have a go myself, I have some friends who are first class machinists who will do the actual work. My thoughts are to try cutting a bolt through the guide rib, index a socket joint from the inside of the bolt and silver solder the joint using the guide rib to ensure alighnment. We would ensure heat applied is minimal and does not reach the ends. I think I would have the bolt handle done first so the bolt doesn't have to get hot again after the shortening process.

I am interested in feedback and other ideas/approaches.

Thanks

Foster

You can find an illustrated article on the subject in The Gun Digest Book of Riflesmithing by Jack Mitchell. His method is to make the cut by extending the extractor collar groove to the desired location and cutting with a hacksaw. The bolt body is then bored to accept the shortened front piece and silver soldered in place. It's neat clean and invisable. Use appropriate heat sinks to protect the lugs.

The firing pin is cut and welded using v blocks.

Make sure, when reassembled, the spring doesn't kink and rub on the inside of the bolt and you're done. The most important, and most forgotten, step is to make and use heat sinks. Too large is just about right.

There is also the Steve Nelson article from the Summer 2008 ACGG, he cut the bolt between the guide rib and the rear lug too.

If you use the "cut under the extractor collar" approach you run into issues with the gas release ports and the firing pin block, all very solvable but illustrates that there are many approaches each with its issues.

Its discussion on the "the issues" I was hoping to generate and learn from.

Cheers

It's been a long time since I've done any of this type work but it seems the firing pin block is unaffected because it is short enough not to come into play until the last 1/2" of firing pin travel. I don't recall gas vents on the bottom of the bolt although I once drilled some just because I thought it a good idea. As I said, it's been a long, long time. I'm hoping to learn from this post and am more than glad to admit my memory deceives me from time to time.

For shortening the firing pin I think you're better off to not cut it / reweld it. If you shorten the back end to the desired overall length all you have to do is recut the cocking piece engagement grooves and you're done. It's fast, easy, and you don't run the risk of a warped firing pin that drags inside the bolt.

Tentman,
If you scribe a witness mark before cutting and use a ceramic backer rod turned to the inside diameter of the bolt, you shouldn't have the misalignment problem. bsteele's fix for the fireing pin is the easiest, and it also works to adapt a standard 98 fireing pin to intermediate length action.
Mike

My response to this thread has bothered me since I posted it. Relying on old memories is a dangerous practice and I apologise for taking that course. My uneasyness sent me back into Frank de Haas's excellent book on bolt action rifles where I am ashamed to say, I learned my response was full of crap. I still don't see the firing pin block becoming an issue because the both the firing pin and the block are relocated by the same amount but there could definatly be a problem with the gas vent. Easy to fix but still there. Again, my apology for posting incorrect information.

Great discussion thanks Guys.

Mike - would you care to elaborate on how the ceramic insert works, I assume you mean in conbination with a TIG weld, and without a socket. Any thoughts on how you would tack then weld ??

Thanks

Tentman,
The backer is turned to slightly less than the diameter of the inside of the bolt,then inserted; the two bolt halves are then adjusted so the witness marks line up.The two halves, having been ground to form a V, can be held in a V-block, vise, or however is convienent to the welder, for tacking together. Once tacked, it can be removed and finish welded.Care should be taken to keep the heat as even as possible to prevent warping.After tacking,though,the alignment and length should be verified. The locking lugs must be kept cool enough to keep them from being annealed. Wet rags(kept wet frequently)and/or "Heat Stop" can be used for this.While they can be later rehardened(surface), it would be a good idea to keep the camming surfaces cool also. It's been a very long time, when I had to work for a living, backer rod was avaliable from "McMaster Carr". BTW the rod has to be left long enough that it can be withdrawn after welding. As an extra advantage, the backer leaves the inside smooth enough that it shouldn't have to be cleaned up.In my,not very well respected,opinion; the best welding procedure would be MIG, then TIG.Gas welding and stick welding have been used,but controling the heat would be harder.As always, someone else may know of a better way.
Mike