Numrich swivel breach

[voyageur1688]

  I have an old Numrich Arms swivel breach rifle that I dearly love but I had the mainsoring fail and have not been able to find a replacement or an affordable gunsmith that can make one for me so I tried it myself with an NOS door lock spring for a 1934 oldsmobile and got it to fit but am having a hard time getting the temper right on it. Any suggestions on what a do it myselfer can do  here?
 Thanks.
 Todd

[Dave B]

This has been covered multiple times  before. The Archives will give you the best results to your question.
For best results with springs you need to get them hot enough(a magnet wont stick to it at that temp) to start with and a good quench (tranny fluid) to make them hardenough where a file wont cut it. Then draw it back to 6oo degrees by lighting off a metal jar lid filled with old motor oil using the propane torch. When the oil is burned off your spring is done. The Archives will give multiple ways to skin this rabbit.

[keweenaw]

Now you are finding out why the gunsmiths charge what they do.  Compared to auto mechanics gunsmiths are cheap.  It may also be that the spring steel in that old Olds spring isn't up to the task.

Tom

[Dphariss]

  I have an old Numrich Arms swivel breach rifle that I dearly love but I had the mainsoring fail and have not been able to find a replacement or an affordable gunsmith that can make one for me so I tried it myself with an NOS door lock spring for a 1934 oldsmobile and got it to fit but am having a hard time getting the temper right on it. Any suggestions on what a do it myselfer can do  here?
 Thanks.
 Todd

The likely problem is the spring is too thin for the job.
If you want to make your own spring order some spring stock from Dixie Gun Works or Brownell's and the booklet on spring making by Kit Ravenshear, TOW has them.
Spring making is not rocket science but it does require some knowledge and the booklet will get you started. You should be able to make a better spring than the one Numrich supplied. Probably broke because it was an unfinished stamping.
It is unlikely that a spring from an automobile door catch is going to work.

If its a coil spring you need some piano wire and mandrel to form it on or see if Numrich/The Gun parts Corporation has a spring that will fit.

As someone else pointed out check the shop time for a parts changer at the local car dealer then wonder what it would cost to have one actually spend an hour or maybe 3 MAKING something from scratch. Based on this a mainspring is worth 50-150 bucks to make.

Dan

[doug]

Then draw it back to 6oo degrees by lighting off a metal jar lid filled with old motor oil using the propane torch. When the oil is burned off your spring is done.

     While I use and recommend the burning oil method, the temperature is 680F if you were using an alternate method of drawing the temper (such as molten lead)  I have tried measuring the temperature of the base of the flame of burning oil, but the numbers I got were considerably higher using one of the high temperature thermometers sold by Brownell's and others

cheers Doug

[Dphariss]

Then draw it back to 6oo degrees by lighting off a metal jar lid filled with old motor oil using the propane torch. When the oil is burned off your spring is done.

     While I use and recommend the burning oil method, the temperature is 680F if you were using an alternate method of drawing the temper (such as molten lead)  I have tried measuring the temperature of the base of the flame of burning oil, but the numbers I got were considerably higher using one of the high temperature thermometers sold by Brownell's and others

cheers Doug

The buring oil method is one that should not work but apparently does at least for some.
This from reading what some scientist wrote about it after burning off a pan of oil and checking temperatures etc.
I would rather use saltpeter, cleanup is a lot easier than oil or lead and I can easily watch the color of the part.
Dan

[Dave B]

Dan,
Is that the same as a Niter blue? I remember some thing about how it melts at around 600 degrees or so. I watched a demo on this at the Oregon Gun makers fair a few years back, they blued up some screws and triggers. Looked slick when they were all done. I assume you can get salt peter from brownells or your local apothocary.