Gunsmithing A Question For The Hide’s Barrel Material Smiths/Experts

[j-dubya]

A question for our industry pro’s and smiths: what are your thoughts the hammer forged stainless barrel that Daniel Defense produces? Does hammer forging 416 stainless offer any benefits, particularly in the accuracy and durability departments?

I ask out of curiosity of the processes. Does hammer forge machine produce a final product that can rival a quality cut-rifled barrel in tolerances and what-not? Does it make the 416 stainless into a more durable product closer to that of say, Bartlein’s new material?

If the huge investment was taken care of for you and you now had one available in your shop and your’e turning out a high end product with it, where would you stack it against your present product made by the conventional smithing?

Thanks for your time.

 

[Blutroop]

I’m real curious also. Tagged

 

[nksmfamjp]

Hammer forging puts stress into the barrel. That stress creates a work hardened hardened material that if the right material is chosen will give you a harder surface which is good for barrel wear, etc.

That stress will release as you are shooting. This will cause poi shift when shooting.

The purpose of cut rifling is to make rifling without putting any stress into the barrel material. This of course leaves the bore surface a bit softer and will have lower wear resistance. Poi will not change with heating, unless the bedding is bad.

 

[THEIS]

Hi,

IMO...
1. Does not rival quality cut rifled.
2. Will not make 416SS more durable than ModBB.
3. Does not offer anything better in accuracy and durability departments.
4. If equipment showed up at my shop ready to hammer barrels...I would stick to gas guns where the precision is not needed.

Sincerely,
Theis

 

[308pirate]

That stress will release as you are shooting. This will cause poi shift when shooting.

You do know that stress relief operations are a thing, and not a new one.

Right?

 

[Davester]

416 is contra-indicated for the hammer forging process. However the process does increase the Rockwell C of the bore by, anecdotally, circa 5 - 9 points which at least infers greater durability. As for accuracy, it is recommended that hammered barrels should be stress relieved which would reduce the hardness/durability gain. Surface finish of hammered barrels is noted to be very good as usually the bores are honed before hammering. The process will taper the bore tighter as the barrel is profiled whereas a buttoned barrel will open up if it is not stress relieved sufficiently. Not tested it myself or seen any research but the commonly held view is that button rifled barrels are the least durable. no idea about Bartlein's new material but I'm guessing it will not be terribly different to premium machine gun steels produced in Europe.

Hammering takes about 3 minutes of production time, far quicker than cut rifling. Usually the chamber is formed at the same time as the rifling which all but guarantees the chamber is concentric with the bore. On the down side the capital investment for hammer forging barrels is huge, not only for the equipment (forge, honing machines, stress relieving ovens etc), but for the premises to house it all. The process is designed to produce large quantities of barrels of a type but not necessarily so easy to produce custom products for the target consumer. Buttoning is far less capital intensive and produces barrels at a similar production rate.

The current paradigm is that hammered barrels are less accurate than either cut or buttoned barrels. My own view that this is probably because hammered barrels are usually aimed at volume markets where cost is a motivating force and corners may be cut to get product out of the door quickly and cheaply. If care is taken really good barrels can be made by the hammering process (Just look at Sako) however, from a marketing perspective overcoming the lack of accuracy belief will be an uphill battle

 

[THEIS]

. However the process does increase the Rockwell C of the bore by, anecdotally, circa 5 - 9 points which at least infers greater durability.

Hi,

If we were talking of durability in terms of strictly wear from friction but in terms of fire cracking due to heat...that is improved how in the hammer process??

The next evolution in barrel making will be in the form of ECM. It takes a couple seconds and produces an absolute stress free product at quality that can exceed cut rifled...but the market is not ready for those prices yet, lol.

Sincerely,
Theis

 

[j-dubya]

Hi,

If we were talking of durability in terms of strictly wear from friction but in terms of fire cracking due to heat...that is improved how in the hammer process??

The next evolution in barrel making will be in the form of ECM. It takes a couple seconds and produces an absolute stress free product at quality that can exceed cut rifled...but the market is not ready for those prices yet, lol.

Sincerely,
Theis

This is where I was looking to go with this thread. My question originally arose with gas guns in mind, even though hammer forged precision barrels are common in Europe (although not stainless that I’m aware of). My experience with using hammer forged barrels in precision applications began a decade ago with Centurion Arms and their product. Ive shot some of DD’s barrels and have a Hodge (FN) and all have been excellent shooters. So I know the process is sound, but longer and thicker barrels are not available.

The fire cracking topic was brought up and is exactly what I am interested in. That and gas port erosion. I also did not mean to elude that a hammer forged 416 is going to equal ModBB or LW50 examples, but perhaps bridge the gap between a standard 416 material and ModBB...

 

[Wannashootit]

Way outside my pay grade, but AFIK, quality of hammer-forged barrels has increased significantly in recent years (including Ruger's).
The GFM hammer forging machines are seven figures, and there's less than two dozen of them in the U.S.

Claiming tolerances of .00001, I'm not aware of any cut rifling process which could replicate that.
Which leads me to conclude that there's more to precision barrels (stress?) beyond variations in land/groove dimensions?

Scroll down a bit, and there's a vid on the process used by DD.

How are Hammer Forged Barrels Made? And Why? | The Arms Guide

the first use of hammer forging in the USA was by TRW on the US Rifle M14 contract. TRW was selected, in part, because it wasn’t a firearms manufacturer,

thearmsguide.com

.

 

[HellcatActual]

You do know that stress relief operations are a thing, and not a new one.

Right?

one could argue , why induce unneeded stress just to hope the the street relief process is 100% effective afterwards?

Im not a fan of HF but again I dont think im good enough to outshoot one. In my expeience, cut rifle tend to perform better. anecdotal at best

 

[Davester]

Hi,

If we were talking of durability in terms of strictly wear from friction but in terms of fire cracking due to heat...that is improved how in the hammer process??

The next evolution in barrel making will be in the form of ECM. It takes a couple seconds and produces an absolute stress free product at quality that can exceed cut rifled...but the market is not ready for those prices yet, lol.

Sincerely,
Theis

Hypothesis is that hammering slightly increases the density of the material thereby increasing heat hardness and resistance to cracking. I'm unaware of any research on that though. ECM takes around 9 - 15 minutes dependant on barrel length, power supply and other parameters, pricing should not be prohibitively expensive.

 

[THEIS]

Hi,

Emag machines are significantly faster than those times and can be setup to do multiple barrels at once.

Do you have or know of a facility over there that has one by chance?

Sincerely,
Theis

 

[308pirate]

one could argue , why induce unneeded stress just to hope the the street relief process is 100% effective afterwards?

I'm not an expert at any of this, but it's my understanding that barrel cold hammer forging offers the best combination of throughput, cost, and repeatability of all barrel making processes.

As to whether stress relief needs to be 100% effective, I don't know if it needs to be. What if 95% effective is good enough?

Cut rifled blanks get stressed when turned to profile. How is that mitigated?

 

[Davester]

Hi,

Emag machines are significantly faster than those times and can be setup to do multiple barrels at once.

Do you have or know of a facility over there that has one by chance?

Sincerely,
Theis

I'm familiar with the EMAG machines, they do not rifle in "seconds". They increase production rates by having multiple spindles in the one machine but even then they do not approach any where near the speed you allude to. EMAG are not the only company with ECM rifling capacity, some have been doing it longer.

 

[lariat]

Cut rifled blanks get stressed when turned to profile. How is that mitigated?

I'm not certain that is true. If done properly, profiling a piece of material will not induce stress as you are only cutting material away. It can remove resistance to the stresses that are already in the blank by way of removing mass and if those stresses that are still resident are in one direction you can get deflection either upon cutting or heating up of the material - i.e., the moving POI.

We stress relieve metal and plastic all the time around here - we cut it to rough dimensions and let it sit to move. Not something you want to have to do with a barrel but it can happen there too and its why there is such a thing as stress relieving.

 

[THEIS]

I'm familiar with the EMAG machines, they do not rifle in "seconds". They increase production rates by having multiple spindles in the one machine but even then they do not approach any where near the speed you allude to. EMAG are not the only company with ECM rifling capacity, some have been doing it longer.

Hi,

Do you have access or know of a shop with ECM setup?

Sincerely,
Theis

 

[Davester]

Hi,

Do you have access or know of a shop with ECM setup?

Sincerely,
Theis

yes

 

[THEIS]

yes

Hi,

PM sent.

Sincerely,
Theis

 

[HellcatActual]

I'm not an expert at any of this, but it's my understanding that barrel cold hammer forging offers the best combination of throughput, cost, and repeatability of all barrel making processes.

As to whether stress relief needs to be 100% effective, I don't know if it needs to be. What if 95% effective is good enough?

Cut rifled blanks get stressed when turned to profile. How is that mitigated?

interesting perspective. I understand and agree, for its process, its king in production environment with relation to barrel to barrel consistency. but I question the added stressed moved into the pipe, then relieved out, is it relieved enough and back into a stable state?

and I would argue the turning process is far less violent in stresses then the hammer. so the stresses either induced or mitigated, unevenly are probably far less impactful. (speculation of course)

I would love to hear Frank Greens opinion on the stress difference.

 

[nksmfamjp]

You do know that stress relief operations are a thing, and not a new one.

Right?

Good luck with that on a hammer forged barrel!

 

[j-dubya]

416 is contra-indicated for the hammer forging process. However the process does increase the Rockwell C of the bore by, anecdotally, circa 5 - 9 points which at least infers greater durability. As for accuracy, it is recommended that hammered barrels should be stress relieved which would reduce the hardness/durability gain. Surface finish of hammered barrels is noted to be very good as usually the bores are honed before hammering. The process will taper the bore tighter as the barrel is profiled whereas a buttoned barrel will open up if it is not stress relieved sufficiently. Not tested it myself or seen any research but the commonly held view is that button rifled barrels are the least durable. no idea about Bartlein's new material but I'm guessing it will not be terribly different to premium machine gun steels produced in Europe.

Hammering takes about 3 minutes of production time, far quicker than cut rifling. Usually the chamber is formed at the same time as the rifling which all but guarantees the chamber is concentric with the bore. On the down side the capital investment for hammer forging barrels is huge, not only for the equipment (forge, honing machines, stress relieving ovens etc), but for the premises to house it all. The process is designed to produce large quantities of barrels of a type but not necessarily so easy to produce custom products for the target consumer. Buttoning is far less capital intensive and produces barrels at a similar production rate.

The current paradigm is that hammered barrels are less accurate than either cut or buttoned barrels. My own view that this is probably because hammered barrels are usually aimed at volume markets where cost is a motivating force and corners may be cut to get product out of the door quickly and cheaply. If care is taken really good barrels can be made by the hammering process (Just look at Sako) however, from a marketing perspective overcoming the lack of accuracy belief will be an uphill battle

So, in your opinion, would a hammer forged 416 barrel (ar15 barrel) resist throat wear and gas port erosion more than a premium button-rifled 416 barrel from WOA or CLE?

 

[308pirate]

Good luck with that on a hammer forged barrel!

Serious question: are you a heat treating professional? A barrel maker?

I'm trying to gage which opinions I should consider and which ones I should ignore.

 

[Davester]

So, in your opinion, would a hammer forged 416 barrel (ar15 barrel) resist throat wear and gas port erosion more than a premium button-rifled 416 barrel from WOA or CLE?

416 does not have the right elasticity to be hammered. So when comparing processes, as most cut/buttoned barrels are made from 416, you are normally inadvertently comparing steels too. 4140 can be hammered, cut and buttoned and would be a much fairer comparison. However in Europe 51Crv4 (6150 equivalent in the US) seems to be the pre-dominant material - which would be tough to button/cut. So to say one is more durable/accurate than the other may be due to the material used rather than the process.

I do recall reading some US military research (That I can't for the life of me find right now so can't quote directly) indicated that the most durable machine gun barrels were hammered, nitrided and then chromed. This research I believe pre-dated the use of stellite liners.

I would stay away from chrome as it degrades accuracy and is porous and while it would increase durability, the accuracy trade-off would not be worth it to me.

All of that being said, if I were running loads of rounds through a semi-auto, a hammer forged and nitrided barrel would be my preference for durability reasons and should be at least sufficiently accurate for that kind of use. IF I were trying to make my AR as accurate as possible and didn't care so much about durability, I would look at other processes than hammered. Not because hammered can't be accurate, I just feel the likelihood of success would be better. A quality hammer forged manufacturer would prove me wrong. Ultimately barrels in the US are relatively cheap, spending a little more for quality product would be good value for money

Just my opinion, hope it helps

 

[j-dubya]

416 does not have the right elasticity to be hammered. So when comparing processes, as most cut/buttoned barrels are made from 416, you are normally inadvertently comparing steels too. 4140 can be hammered, cut and buttoned and would be a much fairer comparison. However in Europe 51Crv4 (6150 equivalent in the US) seems to be the pre-dominant material - which would be tough to button/cut. So to say one is more durable/accurate than the other may be due to the material used rather than the process.

I do recall reading some US military research (That I can't for the life of me find right now so can't quote directly) indicated that the most durable machine gun barrels were hammered, nitrided and then chromed. This research I believe pre-dated the use of stellite liners.

I would stay away from chrome as it degrades accuracy and is porous and while it would increase durability, the accuracy trade-off would not be worth it to me.

All of that being said, if I were running loads of rounds through a semi-auto, a hammer forged and nitrided barrel would be my preference for durability reasons and should be at least sufficiently accurate for that kind of use. IF I were trying to make my AR as accurate as possible and didn't care so much about durability, I would look at other processes than hammered. Not because hammered can't be accurate, I just feel the likelihood of success would be better. A quality hammer forged manufacturer would prove me wrong. Ultimately barrels in the US are relatively cheap, spending a little more for quality product would be good value for money

Just my opinion, hope it helps

Very helpful explanation, thank you. I also finally had some time to have a conversation with Daniel Defense to see what they could offer up. To be fair, when I was using the hammer forged 416 statement above, that was merely an example. DD’s website never specified. Well, the rep I spoke to was very helpful in sharing info as best he could at the level we are talking about here. I am somewhat familiar with materials having worked in metal fab, but I am no metallurgist. He told me they are using ‘APX’ stainless material. Perhaps the experts here can shed more light on that.

 

[THEIS]

Hi,

APX....
APX_GB_01.pdf (aubertduval.com)

Sincerely,
Theis

 

[j-dubya]

Hi,

APX....
APX_GB_01.pdf (aubertduval.com)

Sincerely,
Theis

Thank you!

So in dumbing this down for me, where would this material rank in barrel material (especially in a hammer forged state) compared to other known materials we commonly see turned out from smiths? Say...416 on one end of the spectrum and ModBB and LW50 at the other?

 

[Davester]

Thank you!

So in dumbing this down for me, where would this material rank in barrel material (especially in a hammer forged state) compared to other known materials we commonly see turned out from smiths? Say...416 on one end of the spectrum and ModBB and LW50 at the other?

Not a metallurgist but the short answer is "somewhere in the middle" in terms of durability I suspect. As with most things, a balance is sometimes needed to be struck. Also, it needs to be borne in mind that:

• Material grades allow for a range of composite materials, the same grade from different suppliers could be a little different from each other
• Different batches from the same supplier could also be different
• It is not only the material, but also the heat treat applied to it that will markedly alter the material's property

416r was designed for rifle barrels. It took into account the ease of gunsmiths to machine it and also to be able to get a good surface finish. It's what the market demands, not necessarily the "best" material but what many gunsmiths with 40 year old engine lathes could manage to breech and chamber accurately. As a side note, barrel manufacturers can specify a certain mix of ingredients, close to the established grades from the mill and then market it as something special when the reality is, it is not significantly different from commercially available grades.

"APX" has a little more chromium, a little less iron and more Nickel than 420 SS which is what LW50 is.

The reality is, if you want hammer forged, you will have to take what the barrel maker uses. The number of makers with hammer forges is limited so it will be pretty much take what you're given. I would be interested to know which manufacturers stress relieve after forging. "APX" does not look like a bad choice. IF you can find someone using 33CrMoV12 or similar that would probably be the best as it will take nitriding really well

 

[nksmfamjp]

Serious question: are you a heat treating professional? A barrel maker?

I'm trying to gage which opinions I should consider and which ones I should ignore.

Please disregard my opinion....I’m just an old mechanical engineer who studies rifles as a hobby.

If you could walk into a bar with a test engineer from a top barrel maker, or even a production rifle builder, you would be way better off. The thing is top barrel makers generally don’t have test engineers. They generally just have a handful of folks who know the how/why they make great barrels and some idea how to make more “hummers!”