Read a post in the reference materials links about all of this. I just have a few questions with regards to old milsurp 98 actions:

1) Annealing: I understand annealing an action dead soft makes machining a lot easier, and takes stress out. That sounds good. Does annealing an action help reduce the chances of warpage when you recarburize/harden, or can annealing be skipped?

2) Cryo treating: I've read that cryo-treating can increase the wear resistance of tools. I've read it is used in auto raceing, barrel makeing and several industrial applications. Would there be any benefit here (98 actions), or should this idea be forgotten? Would this be done after all other heat treating/ carburizing procedures were complete, at the very beginning before annealing, or perhaps between annealing and carburizing/hardening.

That about does it for me. That post in the reference section is pretty cool. It just left the above questions in my mind.

quote:

1) Annealing: I understand annealing an action dead soft makes machining a lot easier, and takes stress out. That sounds good. Does annealing an action help reduce the chances of warpage when you recarburize/harden, or can annealing be skipped?

The machining on a Mauser action action will not substantially be improved by annealing. It might be if one is to machine hundreds of them....but the saved dollars won't be worth the time.

As to Heat treating....Don't worry about it.....Let the heat treater do it the way they want.....never spec that you want annealing first...let the experts do it the way they know is best.

I send mine to Pacific Metallurgical and have never had one warped....and have never told them how to do it!.....

quote:

2) Cryo treating: Would there be any benefit here (98 actions), or should this idea be forgotten?

I can find no reason at all for Cryo treating on a Mauser action.

It is my understanding that everything is brought to a neutral starting point prior to heat treating. As far as Cryogenic treatment of firearms go, I've not seen any reputable data showing that it provides enough of a benefit to justify the expense. Were it my personal project I would forgo the process.

IMO, properly heat treating any Mauser action is money well and wisely spent. Cryo, well... (also IMO), is pretty much like pissin' down at rat hole.

quote:

Originally posted by craigster:
IMO, properly heat treating any Mauser action is money well and wisely spent. Cryo, well... (also IMO), is pretty much like pissin' down at rat hole.

Me too. I don't think that cryo is very effective on case-hardened steel; it's my impression that it's intended for homogeneous tool steels that are hardened clear through.
Regards, Joe

On the flip side, there are barrel makers who claim the CRYO treatment will lead to a more stable barrel. I take their word for it. When machinilng down a blank for integral hardware, I always specify CRYO...I too believe there is some benefit (Maybe between the ears).

I have not experienced a warpage with a CRYO'd barrel, but once had a button rifled barrel by a "BIG NAME" that moved so badly I had to scrap the barrel...This one had not been CRYO'd

The extra cost is lost in the round up.

I think steel machines better after cryo. Only anecdotal, but a barrel manufacturer gave me 4 barrels to chamber. He asked me to tell him if I could tell the difference. I was easily able to pick out the cryo'd barrels. That is the only advantage that I have experienced. They don't last longer or shoot better.
Melonite QPQ will give a few mills of hardness and will greatly increase barrel life. It is slick also.
Butch

Annealed receivers are much kinder on tooling.
Cryo changes the crystaline structure of steels,
adding tensile/dimentional strength to an component....tell me how that is not of benefit to an old mauser.
Cryo process should be applied after the high heat treatment has been completed. Post tempering after cryogenic treatment uses a lower heat than that used in the metal hardening heat treatment process.

I know at least one MAJOR and much-respected button-rifled barrel producer who cryos twice, once before and again after all machining is done.

But, I also know of no scientific data that PROVES any benefit to the steel's strength, only to the tool life and machinability of homogeneous tool steels. Apparently it works well enough in at least some cases though, so why not use it?
Regards, Joe

Cyro was the new rage in gun barrels 10-15 years ago. I and a few friends jumped on the band wagon. We found three things.

#1. Bores definitely cleaned better (easier)

#2. Accuracy was just as likely to decline on a barrel as it was to increase on a different barrel.

#3. It turned original blued barrels (pre 64 Win 70 as an example)as purple as a p-poor blue job!!! Ouch that one hurt me!!! 257 Roberts Target model!

Kreiger double cryos for machinability, but still uses the furnace for stress releaving. I have yet to see any scientific data to show that it helps cleanability or accuracy. I have tried it on 25 barrels or so and have also tried the vibration type stress releaving with nothing that I could see changed other than easier to chamber and thread.
Butch

I can't say one way or the other if Cryo treting a barrel is money well spent. I do know it makes a difference on some knife steels.

Might be easier to know by understanding what Cryo treatment does. When steel is heated to it's critical temperature, the grain structure is transformed to austenite. When it is then quenched, the majority of the grains become martensite, but there is always a small amount of retained austenite. martensite and austenite are different in size, with martensite being larger. This is where some of the stress is from after heat treating. Tempering helps releive some of the stress, but without all of the grain being equal in size, it is impossible to releive all of the stress.

Cryo treatment forces almost all of the remaining austenite to become martensite. That is why tooling will last longer with increased wear resistance....martensite is the hard, wear resistent state of steel...more martensite, more wear resistance. Having as much of the steel in the same state, and having the same grain size, reduces internal stress as well. less stress equals higher toughness, another benfit to tooling, and this is where the knife blades benefited as well.

Again, weather it adds enough benefit to a Mauser action and your barrel to have it done is beyond my paygrade, but I can testify that it NEVER hurts.