Finally!

[acidfly]

Finally got my rifle back from the gunsmith. Had a bullet that wasn't sized stuck in the barrel naturally had a few upgrades done aswell. The barrel was cryogenically frozen and had the bottom metal installed. Ordered some AAD mount caps and a Bradley cheek riser. The rifle is a Remington 5r with a Timney calvin elite trigger, the scope is a Vortex Razor 4.5 to 27. Just want to micro slick the bolt and cerakote the stock to match the cheek riser.

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[zombie66]

What benefits does freezing the Rifle/action do?

I have heard of this a few times now and always wondered why.

[acidfly]

Hell if i really know, some science mumbojumbo. Guess I'll see at the range.

[MadPick]

Nice rifle!

How did the bullet get stuck in the barrel? Was it fired normally, but just didn’t exit?

[Arisaka]

What benefits does freezing the Rifle/action do?

I have heard of this a few times now and always wondered why.

I am not a bench rest shooter, but I am a metallurgist. Here is what cryo treatment does in a metallurgical sense:

When you heat steel up to high temp, the iron and carbon atoms arrange themselves into a structure called austenite. When you cool that steel slowly it transforms into ferrite, which has a different structure. And, when you cool austenite quickly, like in a quench, you get a third structure called martensite. This fast cooling traps carbon atoms between iron atoms, and the carbon atoms push the iron atoms out of their usual pattern of straight rows and files, an arrangement also called a lattice. This is important, as an arrangement of straight rows and files is what allows the iron atoms to slide over each other. This atomic sliding (also called dislocation motion) is what makes metal bending and forming possible. Without the ability of iron atoms to slide next to each other, steel would snap like a glass rod

So, back to Martensite. Because the carbon atoms are stuck between the iron atoms, and disrupt the iron lattice, the iron atoms cannot slide easily, Martensite is therefore very hard, does not form well, and is very brittle. To reduce that brittleness, but still retain most of the hardness, martensite is raised to a intermediate temperature. This is called tempering. The heat of tempering provides the energy to allow some of the carbon atoms to move out of the iron lattice, restoring some ductility.

But it turns out that quenching doesn’t always transform all of the austenite to Martensite. Some steel alloys need to be cooled to a lower temperature to allow full transformation to Martensite. This is what cryo treatment does. When you convert the remaining austenite to Martensite you will get an increase in hardness, and may also improve machinability.

People talk about stress relief in regard to cryo processing. Stresses can come about from cold working the metal, or by thermal cycling it quickly. Both of these things disrupt the iron lattice. However, any stress relief at cryo temperatures will be minor. In fact, stress relief is much more effective at high temperatures, as in a process called annealing. Heat is energy, and annealing temperatures provide enough energy to allows atoms to move around a lot, and in so doing restore the iron lattice structure.

The whole deal with cryo and rifle barrels, is the claim that cryo relieves stresses and gives you a more stable and accurate rifle barrel. While I can see cryo improving wear resistance and barrel life by converting retained austenite, I cannot see it doing much for stress relief. So, from a metallurgical standpoint, I would expect cryo to do very little for accuracy. It’s probably more marketing than it is metallurgy.

While I doubt if cryo helps, it wont hurt your barrel either. Go shoot it!

[Traut]

Best explanation I have ever seen, and confirms something I have long suspected.

[zombie66]

Well Thank you for the little science lesson.

[Arisaka]

Well Thank you for the little science lesson.

Proud to contribute to your general fund of knowledge, Jason. I bet you even look smarter now.

[acidfly]

Nice rifle!

How did the bullet get stuck in the barrel? Was it fired normally, but just didn’t exit?

Bought a bunch of used .308 cases. They were cleaned and deprimed also assumed to be resized... wasn't resized.

[acidfly]

What benefits does freezing the Rifle/action do?

I have heard of this a few times now and always wondered why.

I am not a bench rest shooter, but I am a metallurgist. Here is what cryo treatment does in a metallurgical sense:

When you heat steel up to high temp, the iron and carbon atoms arrange themselves into a structure called austenite. When you cool that steel slowly it transforms into ferrite, which has a different structure. And, when you cool austenite quickly, like in a quench, you get a third structure called martensite. This fast cooling traps carbon atoms between iron atoms, and the carbon atoms push the iron atoms out of their usual pattern of straight rows and files, an arrangement also called a lattice. This is important, as an arrangement of straight rows and files is what allows the iron atoms to slide over each other. This atomic sliding (also called dislocation motion) is what makes metal bending and forming possible. Without the ability of iron atoms to slide next to each other, steel would snap like a glass rod

So, back to Martensite. Because the carbon atoms are stuck between the iron atoms, and disrupt the iron lattice, the iron atoms cannot slide easily, Martensite is therefore very hard, does not form well, and is very brittle. To reduce that brittleness, but still retain most of the hardness, martensite is raised to a intermediate temperature. This is called tempering. The heat of tempering provides the energy to allow some of the carbon atoms to move out of the iron lattice, restoring some ductility.

But it turns out that quenching doesn’t always transform all of the austenite to Martensite. Some steel alloys need to be cooled to a lower temperature to allow full transformation to Martensite. This is what cryo treatment does. When you convert the remaining austenite to Martensite you will get an increase in hardness, and may also improve machinability.

People talk about stress relief in regard to cryo processing. Stresses can come about from cold working the metal, or by thermal cycling it quickly. Both of these things disrupt the iron lattice. However, any stress relief at cryo temperatures will be minor. In fact, stress relief is much more effective at high temperatures, as in a process called annealing. Heat is energy, and annealing temperatures provide enough energy to allows atoms to move around a lot, and in so doing restore the iron lattice structure.

The whole deal with cryo and rifle barrels, is the claim that cryo relieves stresses and gives you a more stable and accurate rifle barrel. While I can see cryo improving wear resistance and barrel life by converting retained austenite, I cannot see it doing much for stress relief. So, from a metallurgical standpoint, I would expect cryo to do very little for accuracy. It’s probably more marketing than it is metallurgy.

While I doubt if cryo helps, it wont hurt your barrel either. Go shoot it!

I didnt know the ends and outs, the smith is a very reputable gut here in Bremerton so figured it couldn't hurt.

[jukk0u]

What benefits does freezing the Rifle/action do?

I have heard of this a few times now and always wondered why.

I am not a bench rest shooter, but I am a metallurgist. Here is what cryo treatment does in a metallurgical sense:

When you heat steel up to high temp, the iron and carbon atoms arrange themselves into a structure called austenite. When you cool that steel slowly it transforms into ferrite, which has a different structure. And, when you cool austenite quickly, like in a quench, you get a third structure called martensite. This fast cooling traps carbon atoms between iron atoms, and the carbon atoms push the iron atoms out of their usual pattern of straight rows and files, an arrangement also called a lattice. This is important, as an arrangement of straight rows and files is what allows the iron atoms to slide over each other. This atomic sliding (also called dislocation motion) is what makes metal bending and forming possible. Without the ability of iron atoms to slide next to each other, steel would snap like a glass rod

So, back to Martensite. Because the carbon atoms are stuck between the iron atoms, and disrupt the iron lattice, the iron atoms cannot slide easily, Martensite is therefore very hard, does not form well, and is very brittle. To reduce that brittleness, but still retain most of the hardness, martensite is raised to a intermediate temperature. This is called tempering. The heat of tempering provides the energy to allow some of the carbon atoms to move out of the iron lattice, restoring some ductility.

But it turns out that quenching doesn’t always transform all of the austenite to Martensite. Some steel alloys need to be cooled to a lower temperature to allow full transformation to Martensite. This is what cryo treatment does. When you convert the remaining austenite to Martensite you will get an increase in hardness, and may also improve machinability.

People talk about stress relief in regard to cryo processing. Stresses can come about from cold working the metal, or by thermal cycling it quickly. Both of these things disrupt the iron lattice. However, any stress relief at cryo temperatures will be minor. In fact, stress relief is much more effective at high temperatures, as in a process called annealing. Heat is energy, and annealing temperatures provide enough energy to allows atoms to move around a lot, and in so doing restore the iron lattice structure.

The whole deal with cryo and rifle barrels, is the claim that cryo relieves stresses and gives you a more stable and accurate rifle barrel. While I can see cryo improving wear resistance and barrel life by converting retained austenite, I cannot see it doing much for stress relief. So, from a metallurgical standpoint, I would expect cryo to do very little for accuracy. It’s probably more marketing than it is metallurgy.

While I doubt if cryo helps, it wont hurt your barrel either. Go shoot it!

I'm not a metallurgist, but I did sleep at a Holiday Inn....

I've done some reading on metallurgy, independently of schooling or real need, so my study hasn't been real rigorous but I still have read up some (and forgotten most ) ...But, I have to say... that is one of, if not the best and most easily understood descriptions of those principles!

Now, talk about "normalizing" steel and the formation of carbides!

[Arisaka]

Thank you Traut and Jim! Not many folks are interested in metallurgy. And if all fairness, it doesn’t really come in handy all that often.

[dreadi]

Who did the freezing?

[Rottenryan]

Metallurgy IS FASCINATING...

20+ years ago my first job was working for a metallurgist down in Chehalis. I've spent a career working metal in some form or another. While it's not sexy it is rewarding. Thanks Arisaka for filling in those blanks.