Very, very, very unusual annealing method

[gamestalker]

I have a really strange one for all of you regarding an annealig process. My best friend of over 30 yrs. who is no stranger to hand loading. It begins with necked, tumbled, trimmed, reamed and chamfered brass. He takes his already prepared brass and heats the entire case up until it has been glowing hot for a good minute I would say. Then without any delay he drops it into a bowl of well used motor oil. He performs this process twice and then he rinses it with denatured alcohol or acetone to remove the oil residue. He then tumbles it and when it is finished it looks grey, sort of like steel. When he seats his bullets the neck tension is tighter than anything I've ever felt. But the primary reason he claims he does this is, it stops the brass from ever needing the shoulder bumped, primer pockets don't get loose, and he also claims his brass will out last any no matter what dies they are using. Further more, he is a guy who loads to the extreme, usually exceeding listed maximum data with slow burnng powders for the 7mm rem. mag. being his primary cartridge. The last time I saw him he was using Barns solids and uses the same annealing process as with the brass claiming improved accuracy.
Have any of you ever heard of anyone else using a simular or the same method and if so, is there any truth to this. Even though he is a long time trusted best friend, I just can't muster the nerve to try such an off the wall method of annealing for fear it may cause a catrostrophic case failure and possibly result in excessive pressures that could damage my firearm. He has never had any of his expensive rigs damaged by this process so far as I know, and he is still using this same method of so many years. He is a very level headed individual who has all of his marbles, none missing.

 

[Owen]

interesting. I'm going to have to pull out my heat treating book to figure out what he's doing to the metal.

It actually sounds like he's hardening, not annealing.

 

[rodregier]

I would be leary of any method that anneals the case base. The manufacturing work-hardening of the bases is part of how a cartridge case can sustain the working pressures. Annealing that includes the base of the case negates that feature.

I would expect to see issues with loose primer pockets and maybe even web blowouts with brass *overall* annealed.

 

[Jim Watson]

That is the weirdest thing I have ever heard, at least about case annealing.
Everything in print emphasizes the need to not get the casehead hot because of the risk of head separation and/or blown primers.

 

[GaryL]

I don't think it would be that risky to try, with mild loads.

interesting. I'm going to have to pull out my heat treating book to figure out what he's doing to the metal.

It actually sounds like he's hardening, not annealing.

I agree with you. Let us know what you find out.

I wonder if he isn't adding a temper to the brass, almost like a poor comparison to spring steel.

 

[Walkalong]

It actually sounds like he's hardening, not annealing.

Yep, but I don't know about hardening brass. That method will certainly harden steel.

Since he hasn't blown himself up, I would assume he is not ruining the strength of the case head. With increased neck tension, it certainly sounds like it is strengthened.

Very interesting indeed.

 

[TonyT]

I would never attemt any annealing procedure which causes the head of the case to get red hot. I have only used neck annealing bu standing cases in water to prevent the case head from overheating.

 

[kludge]

Case brass can not be hardened by heat; only by cold working can you harden brass.

Once the case head is cherry red the hardness is removed from the brass.

What he is doing is foolish and very dangerous. He is trying to "temper" brass like you would to carbon steel. It doesn't work that way.

 

[ambidextrous1]

I believe owen has the right idea: Gamestalker's pal has found a way of producing a uniform hardness (maybe 'half hard') in his cases. Performing the process twice ensures uniform hardness throughout the case. The use of used motor oil is a thrifty, but not necessary operation; new motor oil, fresh from the can. would produce the same result.

It's important to acknowledge that gamestalker's friend has repeatedly demonstrated that this is a safe and useful treatment; it's difficult to argue with empirical evidence.

We could learn a lot more about the process through inexpensive hardness testing of treated and untreated cases; I hope that will be performed.

I can't explain the change in color of the cases; gamestalker, is the case color altered by tumbling the cases after heat treatment?

As with any reloading procedure, it's wise to proceed slowly with new ideas, but the process appears to have merit. We need to know more, with a few lab test results. It's your move, gamestalker!

 

[Owen]

The color change is either from oxidation, caused by the heat (look at military brass, specifically the necks)

The other possibility is that he is managing to introduce some carbon, via the dirty motor oil, similar to a case hardening operation, but it doesn't sound like the time is anything like what would be required to that to take place. Also, I have no idea what alloying with carbon would to to a copper alloy.

My gut is that kludge is correct, and he is annealing the whole case. My vague memories all those years ago was that the only way to harden copper alloys was by work hardening. heat will only make it softer.

Makin case neck softer is after all the intent of neck annealing. The point is to make the neck softer so it can be sized more times before the neck splits.

Doing the process twice is pointless, unless he's successfully adding carbon.

its true he hasn't blown himself up yet, but that doesn't mean that the process works. Without more and better documentation, it just means he's lucky.

 

[ReloaderFred]

I fully anneal brass pistol cases to make bullet jackets in a kiln. By bringing the kiln temperature to 1,200 degrees F (648.89 C), the entire case is glowing red. It doesn't matter whether you quench the brass or let it air cool, it's going to be dead soft when done. Quenching doesn't affect the end result when annealing brass. It's so soft you can crush it with your fingers at the case mouth, and when run into the swaging die, the solid case rim can be swaged out several thousandths of an inch. In the case of swaging .410 caliber bullets from 9x19 brass, the case rim is expanding .007", and in swaging .357 bullets from .380 acp brass, it's swaging down .017" at the rim and web. When I make .429" diameter bullets from .40 S&W brass, I'm swaging the base of the case out .005", which is actually quite a bit for that much brass.

I've also turned a case around with a seated core and run it into the swaging die base first. This puts the solid brass of the case as the nose of the bullet and I've been able to reduce the solid brass to a bullet nose. That can only be done with dead soft brass that has been annealed.

If the brass was being tempered, I wouldn't be able to move the solid brass those amounts in either direction. Now I'm not a metallurgist, so I'm only going on experience. I would like to see some input from a metallurgist, though. Perhaps there is another scientific explanation for what the OP's friend is doing, but it goes contrary to everything I've read and done with annealing brass.

Hope this helps.

Fred

 

[popper]

used motor oil has lots of carbon and nitrogen compounds in it. Case hardening, nitriding, martenisitcs from what I remember, are surface treatments. Oil is used for tempering (quenching) steels due to the non-boiling characteristic, if i remember correctly. My guess is that he stress relieves it and then re-hardens it, which would do the job.

 

[ReloaderFred]

But you can't reharden brass by heating it like you can ferrous metals. I've annealed copper, brass and aluminum for making bullets and gas checks, and heating non-ferrous metals softens them, no matter how they're quenched, or what they're quenched in.

I'm still waiting for a metallurgist to explain what happens in this process.

Hope this helps.

Fred

 

[brickeyee]

Brass does NOT harden by quick cooling.

In steel you are altering the structure of the metal by heating, and quick cooling essential freezes the structure.

Brass only wokr hardens.

 

[918v]

I have consulted metallurgists.

 

[hapidogbreath]

I'll talk to my brother.... Quality control Engineer in both destructive and non destructive He knows metals.

 

[rondog]

Hope y'all don't mind if I shoot at a different location......

 

[blarby]

I'd guess your friend has very effectively carbon-bonded his hot brass.

Nifty.

I would be leery of using these cases scratched, as it sounds like he's basically created a soft-metal carbon glaze.

God knows what else is in the oil thats helping him create the short-set glaze, but i'm betting its silicates and sulfites.

Doing it twice would fuse and melt the original glaze to the semi-porous (when red hot) brass, and allow an additional coating to lock in with the second drop.

Neat trick !

918- Please let us know what the metal gods say !

 

[amlevin]

I'm with rondog. I'll move on down the line from this guy. Way on down.

The only thing that has kept him from blowing up something is the rifle(s) he's shooting. A good bolt action with a nice tight fit at the "breech" will keep the parts and gases contained. If shooting a blowback or gas operated action I'd be inclined to want the action covered with a kevlar blanket.

 

[GaryL]

I like to think of brass as the inner tube in a tire. It provides the seal, but the tire provides the structure and the strength. I'm not too worried about soft brass blowing up a gun. Ammo Hot-Rodders, on the other hand, make me nervous.

If the brass were dead soft, I would think the rims would get ripped off the case during the reloading process.

 

[MCMXI]

There's no question that he's annealing the brass irreversibly, but the question to be answered is what are the mechanical properties of brass once carbon atoms occupy interstitial sites in the copper-zinc lattice. The quench time is very short so carbon atoms won't be able to diffuse deep into the brass during the carburizing process. As others have mentioned, he's producing soft brass cases with a very thin carbon rich shell inside and out. This guy may be a genius or a fool. I'm looking forward to reading more posts after some members here have consulted with experts in this field.

But you can't reharden brass by heating it like you can ferrous metals. I've annealed copper, brass and aluminum for making bullets and gas checks, and heating non-ferrous metals softens them, no matter how they're quenched, or what they're quenched in.

I'm still waiting for a metallurgist to explain what happens in this process.

I'm not a metallurgist, but if you look at the phase diagram for copper and zinc, cartridge brass (30% zinc) only has three phases. Those are alpha (up to about 950C), alpha + liquid (about 950C to 1000C) and liquid (above 1000C). So realistically, cartridge brass will always be alpha brass. In other words, unlike steel alloys, there's no phase to heat it too which has superior properties that can be "trapped" in the alloy with rapid quenching. Heat treatment processes of aluminum alloys (T3, T6) often form precipitates such as magnesium silicide which increase hardness, but precipitates don't form when you heat cartridge brass. If you cold work brass you decrease grain size, increase grain boundary density and increase dislocation density. All of these increase hardness and strength but decrease ductility and fracture toughness. If you heat brass to the right temperature range, three things occur, namely recovery, recrystallization and grain growth. The end result of these is a reduction in strength and hardness but an increase in ductility and fracture toughness. Once you've heated brass sufficiently to have all three mechanisms occur, it doesn't matter if the alpha phase cools slowly or quickly because the "damage" has been done and can only be reversed by cold working.

 

[Horsemany]

When he seats his bullets the neck tension is tighter than anything I've ever felt.

This is the part that surprises me. Usually freshly annealed brass feels soft when seating bullets. This method produces the opposite effect? That tells me he's somehow hardening the brass if the neck tension gets tighter.

 

[USSR]

Case brass can not be hardened by heat; only by cold working can you harden brass.

Once the case head is cherry red the hardness is removed from the brass.

What he is doing is foolish and very dangerous. He is trying to "temper" brass like you would to carbon steel. It doesn't work that way.

+1. Your best friend may be no stranger to hand loading, but he is building potential bombs by softening the the case heads of his cartridges.

Don

 

[jmorris]

I am with the rest of the guys, it goes against everything I know and have learned. Good thing the process is much more involved that the way I know works just fine, if it were less work I might have to do some testing of my own.

 

[Greg Mercurio]

1858 got it exactly right. 'nuff said.