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Old December 1, 2019, 06:01 PM   #1
FizzyP
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Button Rifling is Bad?

I picked a barrel I thought would be good for a lightweight AR .308 build. A guy I know immediately shut it down. He said it would only be good for the promised 1 MOA for 500 rds. He blamed the button rifling and recommended Krieger or Hart instead. But Hart makes button rifled barrels! After some reading, I'm seeing that some low end makers will use button rifling because it's actually a cheap-ish manufacturing option and softer grades of steel because then the buttons last longer. So maybe that's the source of the negative reputation for button rifling?

What do you make of this? Obviously Krieger and Hart are respected names and I'm sure they make great products. But they're an order of magnitude more expensive and don't come in lighter profiles. This is the barrel I was looking at:

https://jtactical.com/products/25

1. Is my pick so bad? I have trouble believing it's only good for 500 rds.
2. I'm surprised Juggernaut makes a 1 MOA guarantee without supplying the bolt. Other companies who make such guarantees only do so under the condition that they supply a matching bolt.
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Last edited by FizzyP; December 2, 2019 at 06:54 AM.
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Old December 1, 2019, 06:09 PM   #2
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More on the requirements: this is not a competition gun but I'd like to get 1 MOA out of it. This is a light build. If a $350 barrel weighs 8 less OZs has half the life of a $700 barrel, that's fine with me. I'll shoot it out and replace it. But I will be disappointed if by 1000 rds it shoots 2.5" groups and I can't fix it with ammo selection.
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Old December 2, 2019, 02:58 PM   #3
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I'm not sure who your resident expert is who told you that button-rifled barrels will only be good for 500 rounds, but he is wrong. Button rifling is not a "cheap-ish manufacturing option", it is AN option for manufacturing barrels, and the one that produces the best barrels. Ask yourself "how many match shooting records are held by non-button-rifled barrels?" and the answer will be virtually none. Part of that reason is that there are not very many cut rifling barrel makers, but the most obvious answer is that button rifled barrels are indeed superior to other barrel-making method outputs. Choose any one of the best barrels on the market (Bartlein, Lilja, Hart, Shilen, Douglas, Obermeier, etc) and they are almost all button-rifled. The big exception is Krieger, who does indeed make a good barrel, but by no means a superior barrel compared to the other top barrel amkers. If Krieger barrels were superior, they would be winning more matches than anyone else's barrels. Last time I checked, Lilja had the most record-producing barrels, and Lilja button-rifles barrels. The "cheap-ish manufacturing option" is hammer-forging, which makes a pretty good barrel, but one so full of stresses that they seldom produce optimal accuracy.

The barrel you chose is probably an OK option, you will likely NEVER shoot it out with any reasonable shooting.
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Old December 2, 2019, 04:59 PM   #4
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FWIW,of the named barrels above,Kreiger,Obermeyer,and Bartlein are cut rifled.

But,to answer the OP,not every "expert" friend is an expert.

Scorch is correct in that many very fine,accurate barrels are button rifled.

Last I heard,our Squad Designated Marksman rifles are fitted with Douglas button rifled barrels with a 1 MOA requirement.

I'm thinking the Designated Marksman fires more than 500 rds.

Lilja is a button rifled fine barrel.

White Oak AR barrels are match worty. Button rifled.

I can say I have a preference for cut rifling without saying button rifling is inferior.

As far as the "theoretical" difference,as I understand it,its not as big of a deal with fat bench rest type barrels,but lighter barrels are turned to a contour.

There are two choices. Button rifle before contouring,or after contouring.

Either way has some technical problems regarding stresses (Remember,not a problem for fat contours used in bench rest)

A cut rifled barrel can be profiled,finish reamed,the bore dia lapped ,then stress relieved. Then the rifling can be cut and the bore finish lapped.

The level of stress relief in a cut rifled barrel can be better than in a button rifled barrel,if we are talking profiled barrels.

While that appeals to my mind,I'm sure I do not shoot well enough to see the difference.

I'm not a barrel maker,but I doubt the barrel accuracy life is significantly different if,for example,both barrels are made of 416 R steel and they go through the same stress relief oven,cryo,or whatever other process.

The barrel you linked to is polygonal rifling. I have zero experience with poly rifling,but I'd be more leary of that than whether a barrel is cut or button rifled.

If I were looking for a moderately priced AR type barrel,I'd at least study up on White Oak and maybe Wilson Combat.
I think they both use Wilson button rifled blanks.

If you buy a barrel without a matched bolt (not the best idea) then plan on checking headspace with your bolt. I've had it happen to receive a high dollar custom barrel that was out of spec. You don't know if you don't check.

If you are going to do the check,I suggest tools to strip the bolt.Look at a Sinclair bolt disassembly tool,which compresses the ejector and holds things nicely .
Because they are spring loaded small arts,and you are learning,I suggest ordering an ejector,an ejector pin,an ejector spring,an extractor pin,etc. These can be found as a maintenance kit.
Having the spares beats time on your knees searching.

Good luck!

Last edited by HiBC; December 3, 2019 at 01:42 PM.
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Old December 2, 2019, 08:20 PM   #5
RC20
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There are so many takes on what type barrel and rifling and most of its a load of BS.

Your choice may well be fine, its a new take using polygonel for a 308. Never saw it used for that so its a head scratcher.

Its not the button part its the polygonal. Button rifling if stress relieved works as good as cut and anyone that does it knows that.

Cut rifles have a cost in slow and you have to lap them as they are ugly rough.

So its a coin flip wiht a tiny hair to cut but only for a bug hole bench rest professional.

But a Shilen - Kireger is only about $350 - it would be one I would do some research on to find out.

As far as I know its the only 308 rifle type that uses polygon , all other application I know of are pistol (HK and Glock are two, I don't think much of Glock but I have major respect for HK) . Just because I have not heard of it does not mean its not viable.

They have come up with Many groves (Marlin Micro) two groves (WWII) - 6 grove and myu old 1917 have 5 with left twist and there is ratchet rifling, 5R and god knows what else and it all shoots good and no one is any better than any other - marketing hype to have the latest cool thing to sell more barrel (bless them but I won't pay more for it)

The only one I knew of that had a miner wear advantage was the 5 grove Brit setup used in the SMLE and the Model of 1917 and the P14. Not huge, just wore a bit better but we are talking combat not target.

Barrel Steel: Its all the same, I think Lother Walther uses a bit harder mix. So no, its not going to make a difference.

308 is pretty long lived in the 5000 round + category, ie its not a barrel burner.

I would guess even a match guy would get 3000-5000 before he saw a loss of accuracy and those guys shoot holes in one. I would not see it until it hit 8-10,000.

Cut is a bit more precise and considered a tad more accurate but the button rifled win matches often so its not a major difference and a longer wait.

Bench rest guys will throw a 800 round barrel away when we would take it in a heartbeat.
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Last edited by RC20; December 2, 2019 at 08:27 PM.
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Old December 2, 2019, 08:37 PM   #6
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The Styer AUG Mil-Spec rifle has a cold hammer-forged process. Must admit I am not an expert at all. But viewing the manufacturing in the plant in Austria, and the engineer I spoke to, swore by their quality. And longevity. Is this a superior method?
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Old December 3, 2019, 01:43 AM   #7
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Old December 3, 2019, 02:05 AM   #8
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Old December 3, 2019, 09:13 PM   #9
FizzyP
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Thanks for the advice, everyone. A few points of clarification:

The statement that button rifling is "cheap" is my addition. He didn't say that. And, when I say cheap I don't mean that it's bad. I mean that, from a manufacturing perspective, it is not expensive compared to cut rifling. It is definitely the case that many people are winning competitions and shooting amazing groups with button rifled barrels.

@RC20 The polygonal rifling is a head scratcher for me too. I'm no expert but I've never heard of polygonal rifling on a rifle (TBH only Glock). Regarding Krieger barrels, as far as I can tell the total weight will blow up my build. I just went through their custom order website. The shortest they'll go is 20". Base barrel is $435. Chambering is $100. Fluting it is $160. That's a $695 barrel!

@HiBC I'm looking at Wilson Combat barrels right now. Unfortunately their wesite only lists them in 5.56 and 6.8 SPC II.

Is seriously might just buy this barrel and roll the dice. It's a bit of an unknown but it's can't be that bad and it's not terribly expensive.
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Old December 3, 2019, 11:24 PM   #10
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FizzyP,

There are a lot of apples and oranges being mixed here. The principle problem encountered with button rifling is that because it is a sort of inside-out extrusion process, starting with an oversize reamed bore and then forcing the grooves into the metal by displacing steel that becomes part of the lands, it creates an enormous amount of surface stress in the steel. If you stress-relieve the resulting barrel blank, as Douglas does by exposing it to 1100°F for an hour in an oxygen-free atmosphere, there are no untoward consequences to the button method. Indeed, some rifle builders prefer the burnished surface. But if the blanks are not stress-relieved, as is the case with a good many mass-produced barrels that are not broach cut or hammer forged, then the stresses not only can encourage heat walking, but they tend to expand the bore where the barrel contour is narrowest, causing the muzzle to be maybe half a thousandth wider than the breech end. That encourages fouling with cast bullets, though jacketed ones don't usually care too much about it.

So, I would not hesitate to get a button-rifled barrel or blank (if you have a lathe for contouring the blank) as long as it was stress-relieved, and, indeed, I have a Douglas 6.5 mm premium air gauged barrel that shoots very well. Douglas holds dimensions by process control, but other custom barrel makers will make the barrel slightly undersized and then hand lap it. A hand-lapped barrel's dimensions are essentially indistinguishable from any other hand-lapped barrel's final dimensions if the rifling styles are the same, regardless of the rifling process involved, so I would say all such barrels are virtually equivalent.

In a Precision Shooting Magazine article in the late '90s, Kevin Thomas, who worked at Sierra at the time, did some extensive testing at their indoor range to show a chrome-moly steel barrel chambered in .308 will typically last about 3,000 rounds at peak accuracy. A stainless barrel would go about 3,500 rounds, and if the stainless barrel was cryo-treated, it would last about 4,000 rounds. Unfortunately, he didn't try cryo-treating chrome-moly. I say that because there are reports that it responds more and better to cryo-treating and may outlast a cryo-treated stainless barrel, but I don't know that for a fact.

An exception to all the above is Boots Obermeyer's 5R rifled barrels, originally developed for the M24 sniper platform. He makes his bores 0.002 narrower than standard and uses a cut rifling process to cut to normal groove diameter, leaving lands that are 0.005 tall instead of the usual 0.004", which he says his testing has prooved last longer. He also slopes the sides of the lands rather than making them sharp, which Obermeyer says he can see on recovered bullets is less prone to upsetting the bullet or having the core strip in a rapid twist. I have seen one report by a former military sniper claiming his 5R barrel still shot well after 15,000 rounds, though military accuracy requirements are not as tight as many target shooters want, so it could have been long-since done as far as the half-moa shooter is concerned. I get expensive barrels cryo-treated so squeeze the most out of my investment, but that's your call, of course.
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