Question about "Cold Hammer Forged" barrels


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mp5a3
September 9, 2009, 12:55 PM
I've seen some of the new BCM uppers with hammer forged barrels, looks interesting, what are the advantages ?

Also, what would be worst to best ?

1. 4140
2. 4150
3. 4150 MIL-B-11595
4. 4150 MIL-B-11595 (Hammer Forged)
5. M249 ???

Is that way off ?

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JohnBT
September 9, 2009, 01:15 PM
In general, the quality of a specific product is more important than how it was made. IOW, a good hammer forged barrel can be better and more accurate than a poorly made cut- or button-rifled barrel.

Without knowing the specifics - and reputation - of each barrel I don't know how to tell them apart, except by price.

John

mp5a3
September 9, 2009, 04:16 PM
Well they're both BCM so quality should be high

taliv
September 9, 2009, 05:17 PM
people tell me all the time that hammer forged barrels are much easier to clean. i've got two hammer forged barrels, but i don't clean my guns, so i wouldn't know :)

SlamFire1
September 9, 2009, 05:32 PM
1. 4140
2. 4150
3. 4150 MIL-B-11595
4. 4150 MIL-B-11595 (Hammer Forged)
5. M249 ???

I really doubt material specifications, like 4140, or 4150 Mil B 11595 have any thing to do with accuracy.

I don't know what you mean by M249.

A tube can made of many different materials. What matters most is the skill of the maker.

I have a hammer forged barrel on my Ruger M77. It is an excellent barrel. I have no idea what material Ruger used, and it does not matter.

http://img.photobucket.com/albums/v479/SlamFire/Ruger%20M77%20Glassbedded/96ReducedRugerM77afterGlassbeddingD.jpg

MrCleanOK
September 9, 2009, 07:01 PM
4140 and 4150 are blends of chromoly steel with different amounts of carbon in them, roughly .4% and .5% respectively. Higher carbon steel can be made harder than lower carbon steel, but these two are close enough that the manufacturing processes used on them will have a greater impact on hardness than carbon content, relative to each other.

MIL-B-11595 would be the military standard which probably defines the material properties (hardness, yield strength, tensile strength, etc.), and maybe the manufacturing process. I'm not privy to this document, so that's all I'm going to surmise about it.

"M249" means the barrel is made from the same steel and given the same treatment as barrels for the M249 squad automatic weapon. I think that usually includes a thicker chrome lining than M4/M16 barrels get. Again, I'm not privy to the standard to which SAW barrels are made, so that's all I'm going to say about it.

Of the 5 options you listed for barrel steel, unless you are running your rifle to its design limits (you'd need an automatic weapon to do this), the differences won't amount to a hill of beans.

gunnie
September 9, 2009, 07:40 PM
..."what are the advantages ?"...

1-consistency on long production runs, less machine operator skills/experience needed.

2-the "hammering" process stress relieves the steel.

3-slight increase in muz-vel, due to slightly tapered bore.

4-above mentioned better bore finish {when new} than most production offerings.

gunnie

Runningman
September 9, 2009, 09:32 PM
This article on barrel making should help you better understand rifle barrels. http://www.firearmsid.com/Feature%20Articles/RifledBarrelManuf/BarrelManufacture.htm

Z-Michigan
September 9, 2009, 09:54 PM
You might also find this discussion interesting:
http://www.m4carbine.net/showthread.php?t=7263

I also agree with this:
Of the 5 options you listed for barrel steel, unless you are running your rifle to its design limits (you'd need an automatic weapon to do this), the differences won't amount to a hill of beans.

And note that some high quality manufacturers, most notably Smith & Wesson and Armalite, use the "inferior" 4140 steel.

browningguy
September 9, 2009, 10:19 PM
By actual count and survey 99.885% of civilian shooters will never see a difference between a 4140 or a 4150CMV barrel. I went and read the forum notes and must say that you should really ignore them (except for Bill Alexanders note). One guy talks about running 500 rounds a month through his AR so he deserves the best, which he apparantly defines as the most expensive. If you are running a few hundred rounds an hour through your AR you would probably see the difference, the rest of us not so much.

As for methods of manufacture hammer forging has been sold as the ultimate in barrel making technology. What it really allows is a large quantity of decent barrels to be made quickly and relatively cheaply. A large percentage of shooters will never see the difference between these and a good button or cut rifled barrel. But for the small minority of shooters looking for the ultimate accuracy hammer forged doesn't get it.

Jim Watson
September 9, 2009, 10:34 PM
2-the "hammering" process stress relieves the steel.

I can't agree with that. Those barrels are full of stresses, one reason - besides cosmetics and advertising - that Steyr leaves the hammer marks showing and does not turn the barrels to a smooth taper.

Maverick223
September 9, 2009, 11:37 PM
I can't agree with that. Those barrels are full of stresses, one reason - besides cosmetics and advertising - that Steyr leaves the hammer marks showing and does not turn the barrels to a smooth taper.Neither can I. I have heard (from good sources...the late Gale McMillan IIRC) that hammer forged barrels have greater internal stress and are therefore less "predictable" than a typical milled (turned) barrel that is either cut or button rifled. OTOH for a "fighting rifle" a hammer forged barrel can be beneficial due to the greater strength (in the event of a catastrophic failure), ether way I'll take a nice cut (or button) rifled barrel over a forged bbl any day (all else being equal). :)

rangerruck
September 10, 2009, 03:34 AM
cut bbls can def be the most accurate. but for a large turnout, hammer forged, can do a huge run, and very accurately, without as many possiblities of mistakes or flaws. and the machinery can make many times more sharp lands and grooves for a longer period of time , than cut or button rifleing can. But the prob is, it is an expensive process, the machinery is anyway, and it takes up more room.
I would say, generally speaking, if you treat your steel like taffy, and heat and cool it, and reheat it at least once, and then let it cool down, and begin the process, that hammer forged, with good machinery, is the second most accurate way to make a bbl., with cut being first. But cut rifleing is tougher to do right, and more labor/time consuming, and more personnel dependent.

Jim Watson
September 10, 2009, 12:44 PM
The main advantage of a hammer forged barrel is a high production rate. I think one of the big machines will turn out a rifled, chambered, and profiled barrel in about a minute and a half. Nothing to do but thread for the action and apply finish.

But the machines are expensive to buy and have operating costs of their own. I read that Ruger had a hammer forge machine in the corner of their plant for four years before economics got right for them to set it up and use it instead of buying button rifled commodity grade barrels.

Uncle Mike
September 10, 2009, 04:31 PM
Hammered barrels have never achieved much favour in target shooting. Whilst their proponents laud the virtues of the mirror finish of the bore and its work hardened surface, which gives long life, the barrels tend to be very variable in the uniformity of their dimensions down their length. Also, because the metal is worked completely throughout the barrel there are considerable radial stresses induced which are difficult to remove completely by the usual stress relieving methods. Stainless steels tend to work harden to a much higher degree than Chrome Molybdenum steels and so do not remain malleable enough to hammer forge. Because of this, it is difficult to make stainless barrels this way. Stainless barrels are being hammer forged, but using type 410 steel which has a lower chrome content than the regular 416 steel usually used for making barrels by other methods.

( The above quote from said article on barrel manufacturing )


As the article runningman provided for us states... hammer forging barrels induces numerous stresses to the barrel, which cannot be removed easily or by the use of conventional methods.

MrCleanOK
September 10, 2009, 07:02 PM
Hammer forging barrels is a cold working process. The steel is shaped to the correct contour by plastic deformation (bending it so far that it won't spring back to its original shape), and this will induce a lot of residual stress. The only way to relieve it would be to heat the barrel to annealing temperature. You'd probably want to heat treat it afterward to regain some of the strength. Unless you have access to a furnace, a heat treating chart for 4150, and the money to buy another barrel when you've screwed it up and can't fix it, I would suggest that you just live with some internal stresses in the barrel. If you have a match gun, put something else on it if you want (cut or button rifling).

SlamFire1
September 10, 2009, 07:13 PM
My bolt rifle gunsmith is starting to make barrels.

All barrels have a certain amount of stress. Just turning a blank into a barrel will change internal stresses.

I asked him about cut rifling, button rifling. He says they are are equally difficult to master.

The quality of the barrel depends more on the ability of the maker than the technique.

Horsemany
September 10, 2009, 07:40 PM
My bolt rifle gunsmith is starting to make barrels.

All barrels have a certain amount of stress. Just turning a blank into a barrel will change internal stresses.

I asked him about cut rifling, button rifling. He says they are are equally difficult to master.

The quality of the barrel depends more on the ability of the maker than the technique.

Couldn't have said it better myself Slamfire. There are plenty of hammer forged barrels that will outshoot button or cut barrels to prove your point. Sako hammer forged barrels make very accurate rifles.

Another interesting view is that of improved hardness from the hammer forging process. I read an article once that claimed bores are 5% harder on a hammer forged barrel. If that's true I'd assume slightly longer barrel life on hammer forgings.

SlamFire1
September 10, 2009, 08:07 PM
I read an article once that claimed bores are 5% harder on a hammer forged barrel. If that's true I'd assume slightly longer barrel life on hammer forgings.

Billets that come from the metal company vary in composition within the billet, so the material will also vary in hardness.

A 5% difference in hardness would be lost in the noise, considering all the varibles involved.

Ghost Walker
September 10, 2009, 08:48 PM
Well, ...... I couldn't agree with you more, Horsemany!

I've been studying this topic for several years, now; and there are, indeed, many variable in either manufacturing process that affect ultimate barrel accuracy.

A hammer-forged barrel is as likely to be adversely affected by: machine wear, sloppy setup, or a continually eroding mandrel a as cut rifled barrel can be by either: misalignment, chatter, operator error, or a dull button on a barrel cutting jig.

Mandrel formed polygonal barrels do tend to seal the bullet more tightly as it moves down the barrel. This is because of the shallower, 'hills and valleys' formed by the polygonal rifling. Still, I personally do not think a particular type of rifling has any greater or lesser effect on barrel accuracy.

(You need to remember that Hart or Schillen barrels are button cut and every bit as accurate as any barrel can ever get!)

What does significantly effect barrel accuracy, especially on longer barrels, is the taper that's applied to either one side of the bore or the other: From inside the barrel this means a larger ID at the chamber, and a smaller ID at the muzzle.

From the outside of the barrel this - usually, but not always - means a gradual taper in the outside OD from the chamber to the bore. All of these different rifling methods use their own particular technique in order to accomplish this. Cold hammer-forging equipment is the most expensive machinery a barrel manufacturer can employ; but, the cost and time for each barrel that is produced is much lower than either of the other conventional methods. (broach, and button forming)

As to whether or not hammer forged (polygonal rifled) barrels are more accurate? They may, or may not be; it all depends on (1) the condition of the shaping mandrel, and (Ready?) who made the barrel. Will a cold forged barrel produce more velocity by sealing the bullet better as it travels down the bore? I'm going to say, 'Yes', but only slightly, and this is because, with other things equal, the ultimate limiting factor is always going to be barrel friction.

Horsemany
September 10, 2009, 09:10 PM
http://http://technology.calumet.purdue.edu/met/higley/Precision%20Shooting%20Magazine%20-%20November-%202005%20(Vol_%2053%20-%20No_%207).htm (http://technology.calumet.purdue.edu/met/higley/Precision%20Shooting%20Magazine%20-%20November-%202005%20(Vol_%2053%20-%20No_%207).htm)

Here's an article about hammer forging. Looks like 3 to 6 points on the rockwell scale are gained in bore hardness. That ends up being much more than 5% increase.

Walkalong
September 10, 2009, 09:18 PM
Sako hammer forged barrels make very accurate rifles.I have an old hammer forged "Bofors Steel" Sako in .222 Mag that is the most accurate rifle I have ever shot, short of Benchrest rifles.

Uncle Mike
September 10, 2009, 09:25 PM
Good article Horsemany...I still prefer cut rifling to all other types...but that's just me.

Horsemany
September 10, 2009, 09:30 PM
Good article Horsemany...I still prefer cut rifling to all other types...but that's just me.

Me too. My 6ppc with Krieger barrel is the most accurate rifle I've ever fired. Smoooooth bore that doesn't copper foul and cleaning patches slide through it like they're buttered. On a mass produced rifle I don't see hammer forging as a hinderance and according to the article may have a few advantages. It's interesting how everything either by design, manufacture, or materials has a trade off.

Uncle Mike
September 10, 2009, 09:42 PM
Yea, there comes a point where quality falls prey to quantity and cost.

I lived 30 seconds away from the Douglas Barrel Manufacturing Plant in WV.
Have taken several tours through it and can say... you would be totally surprised to see the operation.

These folks make some of the very best barrels to be had, and it's done the 'old school' way... no fancy computerized, at least not when I went through it, machines other than measurement machines.

Just pure skill and knowledge.

Horsemany
September 10, 2009, 09:54 PM
Just pure skill and knowledge.

Yeah. Reminds me of a tv show I saw one time with a tour of Savage. They had one older gentlemen who's job was straightening the barrels. He had a jig that held the barrel pointing up around 45deg with a light up in the ceiling. He'd eye down it and bend it according to the shadows his trained eye could see in the bore. His bending tool looked like a giant modified pipe wrench. Not many complaints about the results of Savage barrels either.

JohnBT
September 10, 2009, 10:41 PM
There have been some interesting articles published on hammer forged barrels. This one was in Precision Shooting magazine and was written by a mechanical engineering professor at Purdue and Ruger's forging process engineer.

"Experiments with hammer forged barrels on AR-15s."

http://technology.calumet.purdue.edu/met/higley/ExperimentswithHammerForgedBarrelsonAR-15s.pdf

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