Does button rifling use heat?


December 27, 2006, 05:44 AM
This site says button rifling sort of melts the grooves into a barrel.

And this one says it presses them in.

I've got to ask; is one right, neither, or a little of both?

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daniel (australia)
December 27, 2006, 05:55 AM
The button rifling process is a cold-forming process: the bore is drilled and finished and then the hard button is forced through to press the rifling into the bore under great pressure.

December 27, 2006, 05:56 AM
Chuck doesn't know very much about metallurgy or rifling !! It's done cold with a carbide 'button'.

December 27, 2006, 06:42 AM
It's technically a "cold" process, but the friction and pressures involved will certainly make it FEEL like the barrel is heating up.

daniel (australia)
December 27, 2006, 07:00 AM
It's technically a "cold" process, but the friction and pressures involved will certainly make it FEEL like the barrel is heating up.

Yes, friction may warm things a bit. "Cold" in this context means that the process is carried out well below recrystallisation temperature, and certainly well below melting:)

Mal H
December 27, 2006, 10:39 AM
Rifle barrels are usually made from steel alloys called ordinance steel ...

Chuck doesn't know very much about metallurgy ...Ya reckon?! :)
Either that or he gets his steel from the state legislature.

December 27, 2006, 04:49 PM
Well, that's that then! Anyone know a place selling Rock River .308 barrel blanks? I've heard they use a fancy rifling called 5R.

Jim Watson
December 27, 2006, 09:01 PM
That's Rock Creek. Rock River makes ARs and 1911.

The 5R rifling plan was developed by Boots Obermeyer from the first AK74 captured in Afghanistan. It had a four groove barrel with grooves narrower at the bottom than at the top, thereby causing less stress on the bullet as they engraved and spun it. What had been known in the previous century as "trough shaped rifling." Obermeyer converted it to a five groove plan, called it "5R" for five groove, Russian style, and made very highly regarded barrels from it. Mike Rock at Rock Creek picked up the design and has been making good barrels that way, too. He was in cahoots with Remington for some of their very top end sniper rifles. It is cut rifling, not button.
December 28, 2006, 12:58 AM
That ain't the first time that Ol' Chuckie got something wrong. More often than not I find his conclusions to be based on interpolation of assumptions rather than facts. One of his admonishments is that a long range rifle system should be considered a working maximum at one elevation turret rotation over zero plus one or two MOA. The idea being that you won't have time to crank any further as you're trying to make a 900+ yard hit! The tag a long idea is that he can't remember how many rotations he's made (a simple matter as most tactical scopes have turret markings for exactly this purpose). He frequently assumes that modern methodology = crap despite the evidence to suggest that accuracy standards have continued to climb. All in all I think Chuck's a fool who's gotten more press than he deserves. Better information is availible from gun rags that don't fund his lunacy.

December 29, 2006, 08:38 PM
I'll also add that our barrels were single-point cut-rifled, as opposed to broach-cut. We did also make some low-grade button-rifled barrels, but they were generally of the standard rifling pattern. The story on the 5R contour above is correct.

However, there's another company in Wisconsin that makes a 5R-type barrel using a button, but they call it a 5C ("canted"). Broughton Barrels (billed as a division of North Manufacturing, when there is no other division) actually ripped off the contour from an Obermayer barrel by making a casting of the barrel's bore, which they used to design their "5C" button.

Rock Creek makes barrels that will compete with the best any day of the week in any caliber. But Mike is somewhat unreliable, which means that on the best day humanly possible, only two people will be cut-rifling any barrels. Almost every day, only one guy is doing it.

The result is a long lead time of indeterminate length. If you're comfortable with that, you can get a fantastic barrel. If not, you should really go somewhere else, because this is a problem that will likely never be fixed. People say "never say never," well, I'm saying never.

July 23, 2007, 01:07 PM
I talked to the barrel guy at Delta Gun Shop ( in Colville Washington and he explained the three methods for rifling barrels.

Button Rifling: push/pull a "button" through the bore. This is NOT a cutting process, but more of a metal displacement process. This introduces stresses into the barrel which must be relieved before the barrel contour (outer shape of barrel) is cut. Also, after the stress relief, the bore diameter will change slightly, so this must be accounted for in advance.

Hammer Forging: Didn't really talk about his, but apparently HK uses this method. Also NOT a cutting method. This is a hot forming method and has issues similar (but opposite) to button rifling in bore diameter changes.

Cutting (for lack of a better term): Run a tool down a cold bore that cuts a single groove 1/10 of a thou deep. Index bore, cut next groove. Cut all grooves and then increase depth of cut another 1/10 thou. Do this repeatedly until you are done... apparently takes about an hour to cut the rifling on a barrel. I got to see the guy's setup and he showed me how it worked. Pretty neat! Introduces no internal stress in the barrel as it is a cold process.

For the record, the guys at the Delta Gun Shop kick butt! I needed a place to store my guns while on a trip to Spokane because we made a detour into Canada to see my wife's mom. I asked Jim if I could store my guns with him for the week for a modest fee. He replied that that would be just fine. When I got there, the "modest fee" turned out to be $0.

Jim is a custom gun maker, specializing in bolt action rifles, so it seems (they do a lot of other stuff too) and his rifles look pretty great. I think when I have more cash, I'll turn to Jim for a custom rifle. Great guy.

Jim Watson
July 23, 2007, 01:34 PM
Thread coming back to life, eh?

I wouldn't call hammer forging a hot process except that waste heat from the hammers heats the metal up. Lots of residual stresses. Some makers like Steyr and Ruger on some models leave the hammer marks, just polish and blue over them. Avoids releasing the intense stresses in the steel.

In addition to the above methods, I recall:
Broaching, all grooves cut simultaneously with a stack of cutters gradually getting larger, used by S&W and many minor makers.
Scrape rifling, done like cut rifling but with a different grind to the cutter. It was very slow but very smooth, used only by Springfield Armory on NRA Sporter and match rifles that I know of.
ECM, what the British call "spark erosion", used by S&W on their monster magnums and by Nowlin.

July 23, 2007, 07:35 PM
EDM is 'spark errosion', ECM is Electro Chemical Milling.
Think of plating operating backwards.

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