I love this sort of technical discussion, it’s how we improve our knowledge. First off, I don’t think Barry’s remark about idiots fooling with guns was meant to suggest that we’re all incompetent, rather that there are indeed a few idiots that need to be saved from themselves, and that might well be why barrels are so tight, well beyond the degree of tightness needed for safety. If it emerges as a result of discussion and experiment hat barrels can safely be fitted less tightly it will be an important step towards the sort of home gunmaking that might be necessary in future.
As for Gary and Brett’s comments about professional gunsmiths, I have uncovered a stack of similar stories from reliable sources, and I too have fixed guns that were butchered by some of these charletons.
Gary’s story about plating was interesting. In the last few months I have seen three electroless nickel plated pistols that were corroding under the nickel. It seems that most metals including nickel are porous to some extent and that moisture can penetrate. The nickel was not actually peeling from any of these guns but the corrosion was clearly visible. All were carry guns worn on the right and all the corrosion was on the left side of each gun, obviously from perspiration. Although electroless nickel is a better and harder finish than the electro variety the problem is stripping it if you need to. Electro plating can be stripped by reversing the process but electroless can’t. Brownells has a safe and easy chemical stripper but won’t export it. The only other method I know of involves cyanide. Basically therefore, once you’ve electroless nickelled a gun you’re stuck with it, and if corrosion starts there’s no way to stop it. Hence my preference for old fashioned blueing. Less durable but light corrosion can be polished out and blued about as often as necessary. Can be done at home at minimal cost.
Brett’s comments about the 98 raise interesting points. Truing the receiver ring and internal shoulder is desirable for accuracy provided the possible consequences are understood. 98s were all made from a low carbon steel and case hardened. In some cases, depending where and when they were made, the case is very thin, sometimes as little as five thousandths. Truing the internal shoulder on a lathe would be likely to cut through the case. Such truing is best done by hand with a tool that can be made, and is basically a lapping job. Even then Jerry Kuhnhausen recommends re heat treatment afterwards because of the risk of thinning the case too much. Same goes for truing the receiver ring for the same reason. I set them up on a mandrel in my accurate lathe and check the receiver ring with a DTI. That shows how much out it is. If it’s very slight a little lapping will true it or almost true it without taking off more than a thou or two which can safely be done. If it’s more than that, you can take of the same one or two thou but no more unless you are prepared to have it re heat treated.
The matter of how a 98 barrel should be fitted is simple enough provided you take the trouble to understand the principles. What distinguishes the 98 is it’s internal shoulder. That is the primary tightening shoulder. The receiver ring is the secondary shoulder. That is apparent on all the actions I’ve seen. The tight engagement of the barrel could be seen in the slight depression it had left in the face of the internal shoulder. The idea is to machine the barrel shank to the same length as the depth between the receiver ring and the internal shoulder so that the barrel face and shoulder both tighten up equally. A refinement is to make the barrel shank one thou longer so that tightening is slightly more on the internal shoulder.
Is it important ? I can’t say, but I can’t see why it should be. After all, if the barrel shank is left slightly short you’d have the same situation that you have on all other bolt actions, so I can’t see that it would be a problem. But, as the internal shoulder is there, it makes sense to cut the barrel shank to fit the action in accordance with standard practice.
Barrel threading and chambering is straightforward if you’re doing it yourself. The best bet for most amateurs, however, is to buy a barrel profiled, threaded and chambered. For one thing profiling is a lot of work, and what people like Truvelo charge for doing those things is so reasonable it’s not worth doing them yourself. Ideally, threading is best done to fit the individual action, but the one we’re now working on was prethreaded and seems very accurate despite the barrel and action threads being a slightly loose fit.
Chambering is where it gets interesting. As far as prechambering is concerned there are two ways to go. You order it long or short chambered, about half a millimetre long or short. It should be remembered that it is impossible to chamber to the correct headspace without the action. A long or deep chamber is cut a little deeper than neccessary. The barrel face and shoulder are then trimmed back a thou at a time on a lathe on a cut and try basis till the headspace is right. That’s the cheap and easy way.
A short chamber, which is what we are doing right now, is cut shorter by about half a millimetre. It is finished to the correct headspace with a finishing reamer by hand using a tap wrench, a thou or so at a time until headspace is right. A chamber reamer costs about R1000 which is the disadvantage if you’re cutting only one chamber. Both methods need a lathe for trimming the barrel shank to fit the receiver.
Both also need headspace gauges. Those are not expensive at R300 a pair, and the go gauge is sufficient on it’s own.
Chambering and headspacing is easy and well within the ability of anyone with handyman skills and the necessary theoretical knowledge.
BTW it’s interesting that Brett’s 98 that was heat treated again was made in 1944. Quality began to deteriorate from 1941 and was very poor in some factories by 1944. That would probably explain the need to re heat treat it. All 98s are now more than 50 years old. Most are well used. All should be approached with some circumspection. Generally though, those made before 1941 right back to pre WW1 are usually OK if they are visibly in good condition and haven’t been worked on by some incompetent who might have left them unsafe in certain respects. To those who are interested in the finer details of the 98 I strongly recommend Jerry Kuhnhausen’s ” The Mauser Bolt Actions.” The detail is extreme and exceeds everything I’ve got from all other sources combined.
[Originally posted to SATalkGuns -- Admin]