Re-barrelling a K-98

[Bruce_in_Oz]

I have a "Russian re-work" K-98 here with a barrel that is not only a little "shabby" internally but has WAY too much headspace.

Pulling and replacing the barrel is not the issue; I "have the technology", (thank-you to the nice folk at Brownells).

The trick seems to be removing the sights and re-fitting them on a replacement barrel, of which I have several.

The SMLEs and No4's I usually have on my bench don't have their sights soldered on.

Any clues as to how best tackle this? I have been told to pack the bore with finely-crushed charcoal to reduce nasty oxidization effects from the heat needed to remove and install the front, and especially, the rear sights.

Any advances?

Information

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[Doco overboard]

A mixture that can be used to protect scaling on the inside of a barrel for soldering is one part lamp black, one and one half parts of ordinary kitchen flower and two parts table salt. Mix into a thick liquid or thin paste and coat the inside of the bore where it is going to be heated. I have used it myself for soldering ribs and site blades on Muzzle-loader rifles. On a rib you must maintain a constant heat source to avoid a cold joint which will not hold from vibration. Mauser sight bases as best I can tell are soft soldered because I have removed them with a propane torch. Map gas may be better because of the mass of the barrel. The real trick is going to be indexing the base when it is refitted because you can prep the base surface and tin it but it has to be straight. I don't think it will take nearly as much as what the factory used to get a solid fit but it will definatley make you appreciate the craftsmanship of the factory workers. Maybe polish and fit plumb flux and then sweat the base on like cu pipe. I would pull the barrel check the lugs for setback, and then do the barrel then re-install. You may have a soft receiver or a bad Russian gunsmith.

[Calif-Steve]

Not the way to go. You remove old barrel and fit new barrel. How many degrees are you off? You put it in a lath and remove the slight metal to fit the new barrel. You have the gunsmith schooling, right? Now you know why a gunsmith charges for the job.

[Doco overboard]

12 tpi thread on a large ring barrel stub should advance barrel 1/12" per 360 deg I think 8.62 deg equal about.002 crush. Should give you about 40 ft/lbs on the inner collar and not over-stress the receiver threads. I'm not a gunsmith by trade but if you got a lathe to play with you can do more than just fit barrels., and I certainly would not hobby a Mauser sight base with a lathe if I didn't need to but would like to help a guy with a question.
Thanks, Brian

[Bruce_in_Oz]

Fitting and headspacing / re-chamberiong barrels are familiar jobs.

Soldering on large-surfaced "attachments", like Mauser rear-sight bed, less so.

Back when the world was a better place, I mainly worked on M-14s, L1A1s and the like; not a lot of soldering going on there, or "restored" occasional Lee-Enfield "sporters" to as close to their former glory as was possible. The sight beds on a Mk1 LE are somewhat less of a challenge than a Mauser type, which were obviously designed to NEVER fall off.

I seek enlightenment to avoid tears before bed-time.

[Calif-Steve]

Everybody tells me the rear sight assy. melts off right now. Also hear the front sight will not easily come off. Applying lots of heat to a nice, new barrel muzzle makes no sense. Find a gunsmith and have him do the work. I am a student at Lassen CC gunsmithing course. We do not melt barrels, that is what they teach to us.

[Claven2]

FWIW, I've done a good many of these and the soft solder used on the sight bases and the thin metal of the bands themselves only needs propane heat. I've never had to pack the bore with anything, the heat won't get high enough for long enough to risk scaling.

Basically, you install and headspace the barrel and the sights will en up wherever they end up. Then you melt the solder and rotate the sight to wherever it needs to be. You will have to carefully drill a locator dimple through the threaded hole for each sight without messing up the threads (I use a mill), and then re-install the set screws.

It helps pt have 2 people as you will need parallel bars, a torch and a means of turning the base once the solder flows. Hold the barrel in a vise and clamp your first parallel bar to the bottom receiver flat, just behind the recoil lug, index everything to that.

Good luck.

PS: Facing the back of the barrel and the receiver facing shoulder on the barrel can also be done, you then would need to ream the chamber using a reamer that (hopefully) closely matches the original military reamer the factory used. This is what I would do on a sporting rifle with a known tight SAMMI chamber, but on the K98k surplus barrels, I find it's less work to re-index the sights if the headspace is good when I breech up the tube.

YMMV.