Fluting then Cryo treating?

[wyobohunter]

If I have my barrel fluted, should I also get it cryogenically treated?

[Harry Bonar]

Sir;
Respectfully, No, I wouldn't bother. A barrel properly stress relieved is sufficient although it's claimed that it does help accuracy.
Properly shooting a barrel and then properly cleaning it always seemed to work for me - but what do I know!
Harry B.

[HiBC]

I am going to say some things that might be wrong.I am not a barrelmaker.I did spend 30 years cranking handles and making chips.
My mind tells me retro-fluting is questionable.I know Schneider barrels does it early in the process.
Here is my thought.There is no such thing as a perfectly sharp cutter.Most carbide cutters are abit "dull" on purpose to make the cutting edge more durable.So,while the do a great job of cutting away material,some degree of displaced material occurs.Think peening..Are you familiar with a tool called a nut splitter? or have you ever smacked a chisel in the middle of a nut flat to expand and loosen the nut?It is likely that cutter buzzing down the barrel on the outside will affect the bore a little bit.Probably make it grow.And,the cut will probably stretch some steel length,like stroking down a piece of clay or rolling dough.You will likely create some stress or lack of straightness.Maybe very little.AS the cuts dont go through,likely you would have no effect at the throat,an expanded bore for most the lenghth,then a little choke effect in the last few inches at the muzzle.
Will it matter? I don't know.Myself,If I wanted fluting,it would be a step in the barrel creation,not an add on.
I do not know enough about cryo to comment.

[VaFisher]

I am going to say some things that might be wrong.I am not a barrelmaker.I did spend 30 years cranking handles and making chips.
My mind tells me retro-fluting is questionable.I know Schneider barrels does it early in the process.
Here is my thought.There is no such thing as a perfectly sharp cutter.Most carbide cutters are abit "dull" on purpose to make the cutting edge more durable.So,while the do a great job of cutting away material,some degree of displaced material occurs.Think peening..Are you familiar with a tool called a nut splitter? or have you ever smacked a chisel in the middle of a nut flat to expand and loosen the nut?It is likely that cutter buzzing down the barrel on the outside will affect the bore a little bit.Probably make it grow.And,the cut will probably stretch some steel length,like stroking down a piece of clay or rolling dough.You will likely create some stress or lack of straightness.Maybe very little.AS the cuts dont go through,likely you would have no effect at the throat,an expanded bore for most the lenghth,then a little choke effect in the last few inches at the muzzle.
Will it matter? I don't know.Myself,If I wanted fluting,it would be a step in the barrel creation,not an add on.
I do not know enough about cryo to comment.

I have been making chip's myself for little longer then yourself and when I saw your post I thought I would be surprized if anyone would beleive you.
Well I am here to back up your statement's sir.
Now with that being said most that would not understand will say you are wrong but in fact you are right.
After a barrel has been fluted it could be a issue with it being accurate or not with most factory load's not to say one couldn't custom load for it.
Cryo treatment of the barrel afterward would not help with any damage done during flutting. With that said cryo has it advantages also, it changes the mole struckture of the m aterial like heat treatmen would but does not anneal at all.

[Harry Bonar]

Sir;
Couldn't agree more.
Harry B.

[Alleykat]

Once again, I'm sure I'm missing something that's obvious to the rest of you guys, but what does chip making have to do with barrel fluting? How are the technologies related?

FWIW, I believe most barrel manufacturers recommend against post-manufacture/rifling fluting of a barrel.

Also, contrary to information provided by Bushmaster on their website, fluting does not "stiffen" a barrel.

[VaFisher]

Once again, I'm sure I'm missing something that's obvious to the rest of you guys, but what does chip making have to do with barrel fluting? How are the technologies related?

Sir chip making is machining of materials, metal, plastic, ceramic along with a host of others and sir that's what flutting a barrel is ( Machining the barrel in such a way to make flute's ) and that's why it's related.

Cyro is very much like heat treating or at least you can get much more life out of some tools that were HT and then Cyro treated, it changes the structure of the metal's if you would same as HT but the opposite prevails and it really works.
I would suspect a barrel that has been Cyro treat would last a lot longer, I don't know of anyone that will shoot enough for this to be of any help unless you are shooting at high speed 4000 fps or faster it may help where you can see a difference before burning the barrell out. I feel sure someone out there may fit in to this enough to see, but how are you going to measure the difference unless you do a test of some sort and publish for all to see.

[grymster2007]

I use a key cutter in carbide.

Very astute, LongRifles! Spoken like a true machinist!

I found this article on cryo treating, discussed the process with an engineer friend who more or less confirmed the gist of the article.

cryo treating

Here's what Lilja, maker or world record holding rifle barrels, has to say about cyrogenic treatment:

"The cryogenic treating of barrels at a temperature of -300 degrees below zero [77K] has been a hot topic of discussion lately. Our short answer is that it will not harm your barrel but we are not completely convinced of all of the benefits claimed by some. The only benefits that we feel are likely to result from the treatment are possibly a longer barrel life and a slight increase in machinability."

Claims for increased accuracy through stress relief are not founded in our opinion. When barrels are button rifled no material is removed, it is just displaced. This causes stresses to be formed in the steel. If these stresses are not removed problems will result. These negative conditions include warping of the barrel during other machining operations, an increase in the bore diameter towards the muzzle end of the barrel during the contouring phase, and in the extreme, lengthwise splitting of the barrel. Also, if there are stresses remaining in the barrel they can be slowly released as a barrel warms up during firing. This causes the barrel to actually move during the course of shooting, causing inaccuracy."

In our testing we have found that the only effective means to completely remove the types of stresses introduced during rifling are with conventional heat treating using elevated temperatures. The -300 degree treatment alone will not remove these stresses. We have been told by a knowledgeable metallurgist that the deep cold treatment will, at best, remove up to 6% of the remaining stresses in the type of steel used for rifle barrels. The key words here are remaining stresses. In other words if the barrel was not stress relieved conventionally, then only 6% of the original stress will be removed. If the barrel has been treated conventionally with heat and then brought through the -300 degree cycle, up to 6% of any remaining stresses could be removed by the cold treatment. We do know through our testing that the cold treatment alone will not remove any significant amount of stress and that the problems outlined above concerning stress will remain in the barrel."

So, because of the very limited amount of stress that could be removed with the cold treatment (if the barrel has been properly stress relieved with heat as our barrels are) we do not believe that there can be much if any accuracy benefit to the -300 degree treatment of our barrels. It is for these reasons that we feel the cold process has very little potential for increasing the accuracy of our barrels. In our opinion, other than the removal of these stresses, there are no other mechanical factors involved that could benefit accuracy in a rifle barrel, resulting from a heat treating operation, either hot or cold."

[Alleykat]

Sir chip making is machining of materials, metal, plastic, ceramic along with a host of others and sir that's what flutting a barrel is ( Machining the barrel in such a way to make flute's ) and that's why it's related.

Thanks for the info. I knew, of course, what fluting a barrel involved, but had no idea that the manufacturing of chips related in any way to fluting barrels.

[HiBC]

I wouldn't even think of approaching it with a ball mill!!
"Making chips" is just a euphenism between trades folks.It is the equivalent of a cabinetmaker saying he is making sawdust for a living.Its a joke.

I attended a Makino High Speed Machining seminar in Denver once.15 to 20 thousand RPM air spindles,but light,(.020) cuts and very high (200 ipm) feeds.
Only air for coolant

Had some barrels to octagon.Just a straight taper.
Machined them clamped to the table on a Bridgeport,sidemilling with a new 3/8 carbide Tin coated end mill.Ran it up in the red for RPM ,over 3000.Feed was fast,maybe 12 to 16 ipm,and cuts about .015 deep.
It worked beautifully!!! Airjet kept the chips clear,and the table was a great heatsink.everyting stayed cool,surface finish was great.Completed 2 bbls in an evening after work,very fast.

[grymster2007]

15 to 20 thousand RPM air spindles

We have a Yasda YBM950 with a 20K RPM Big Plus spindle. Awesome machine! I wish I could use it for personal stuff; I'd make a lot of cool gun parts! But alas, no go.

In Chicago last week, Yasda told me that next month, they were coming out with a 60K RPM five-axis machine with one arc-second accuracy on both the rotary and trunnion axes. That, along with their sub-micron-accurate linear axes should make for about as good a five-axis machine as can be found.

Don't think one would need that level of accuracy for building gun parts, but then again, it wouldn't hurt!