Strawing of small parts question

[Baskerville]

Hi guys,

I would like to take the extractor from my Husqvarna 1640 (small ring Mauser) and apply a "straw finish" as was used on Luger small parts like the trigger, take down lever, etc.

One recipe for achieving the straw color I have read is as follows: polish, degrease part, place in oven at 450 degrees for 15-20 minutes.

My question is, however, will heating the extractor in this way somehow alter its temper or integrity? I'm afraid I know nothing about metallurgy or heat treating, so I don't want to do something stupid just to achieve a pleasing finish on this important part.

Thanks,
DeWayne

 

[Baskerville]

Well, never one to wait when I could just dive in I went ahead and strawed the extractor and collar in the oven - 450 for about 25 minutes. I am well pleased with the results. To my eye, looks just like the Luger parts strawed back in the day. I learned a new skill today!

 

[john.k]

Collar looks to be a cheap pressing ,rather than the machined collar Im familiar with ...........never the less,its not a highly stressed part,so it will be OK..........In my experience ,the collar should not be removed without good reason,as they never sit tight in the groove like a factory fit,

 

[Baskerville]

Standard Husqvarna extractor collar. Went back in perfectly fine and tight as it was when I removed it.

 

[trevj]

Well, never one to wait when I could just dive in I went ahead and strawed the extractor and collar in the oven - 450 for about 25 minutes. I am well pleased with the results. To my eye, looks just like the Luger parts strawed back in the day. I learned a new skill today!

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Yes it affects the temper, but, the color is a direct result of, and an indicator of, the correct temper of the parts, too.

There is a whole spectrum of color available from different levels of heat, you can read up on it by looking for a "Tempering by color" chart. The deep blue screws that Colt's Firearms and others used, were done with heat too.
The only down side, other than maybe the color you wish, being beyond the required temper of the part, is that the oxide layer formed on the part, is not very wear resistant.
From experience making tools in a forge, a straw temper was pretty low draw, as far as softening the part. We used it for tools like cold chisels, to just reduce the hardness enough that it was still a good working cold chisel, but was far tougher and durable, than a glass hard part from the quench.

 

[Baskerville]

Thanks for the info. Yes, I was aware Colt's "fire blue" was also heat process, and in fact, I had one of these extractors fire blued a few years ago. It was beautiful, but yes, thin and fragile.

As to temper, I suspect I'm ok. I note Lugers used to have strawed extractors, so I reckon this one will be fine. At any rate, it's not a dangerous game rifle, so my life will never be depending on it!

Thanks,
DeWayne

 

[trevj]

Thanks for the info. Yes, I was aware Colt's "fire blue" was also heat process, and in fact, I had one of these extractors fire blued a few years ago. It was beautiful, but yes, thin and fragile.

As to temper, I suspect I'm ok. I note Lugers used to have strawed extractors, so I reckon this one will be fine. At any rate, it's not a dangerous game rifle, so my life will never be depending on it!

Thanks,
DeWayne

It's kinda hard to go too far wrong, following what the old school guys learned to have worked, the hard way!

The exact same temperatures, without any air exposure, would give you the exact same results, but without the added colors!

So, you picks, and you chooses!

 

[john.k]

Alloy steels colour different to carbon steels ,and its not wise to rely on temper colour .