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Posted: 11/6/2001 4:31:19 AM EDT
I've always been curious about how they rifle a barrel. Could someone give me some info on how it's done?
Link Posted: 11/6/2001 4:50:07 AM EDT
The most common way is to pull (sometimes push) a cutting tool through the drilled hole. Many variations exist of this process, some cut all the grooves at once, some cut one at a time. The tool is tristed as it's pulled.

Another method is to hammer a hot blank down over a mandrel with ridges on it. This one's called hammer forging.
Link Posted: 11/6/2001 5:38:36 AM EDT
[Last Edit: 11/6/2001 5:37:48 AM EDT by fight4yourrights]
also button rifling, where you "push" the grooves into the barrel.


goto www.riflebarrels.com/twistmachine.htm to view one method
Link Posted: 11/6/2001 6:35:30 AM EDT

Originally Posted By fight4yourrights:...goto www.riflebarrels.com/twistmachine.htm to view one method



OT, but the first photo gave me a smile. I have a milling machine almost identical to the one in the first photo.
Link Posted: 11/6/2001 7:05:43 AM EDT
Button rifling cuts all grooves at the same time using progressively deeper "buttons" indexed on a mandrel which is pulled through the bore. The pitch is dictated by the angle of the cutters on the buttons.

Broaching is another method where grooves are cut one at a time. The first groove is used to index the rest. Pitch is determined by the operation.

In days of old, the blank was forged over a hexagonalor polygonal mandrel to create the bore. The mandrel was removed and the barrel was brought back up to forging temperature and twisted to form the rifling. The exterior of the barrel was cold finished by grinding and filing.
Link Posted: 11/6/2001 7:11:58 AM EDT
[Last Edit: 11/6/2001 7:15:14 AM EDT by fight4yourrights]

Originally Posted By Keith_J:
Button rifling cuts all grooves at the same time using progressively deeper "buttons" indexed on a mandrel which is pulled through the bore.



No, everything I've read indicates that button rifling "pushes" the grooves into the barrel. No material is removed from the barrel, it's a cold forming operation.

Check out what the website I referrenced says about it:


Secondly, stress can be formed in a rifle barrel during a cold forming operation, such as button rifling. Since no material is removed from the barrel when the rifling is formed, rather it is displaced, it causes compressive stress in the steel.


Here's another good site www.nwprecisionbarrels.com/tour.html,

Or Fulton Armory www.fulton-armory.com/Barrels.htm which states:


They must be buttoned with thick walls, otherwise the process will bulge/distort the barrel blank wall.


Here's another article www.riflebarrels.com/barrelmak.htm

Link Posted: 11/6/2001 8:05:13 AM EDT
THX for the info.
Link Posted: 11/6/2001 10:12:38 AM EDT
If you are interested in actual instructions for making barrels and rifling machines check out hppublish.com/
It looks like their catalog is down right now, but they have some very worthwhile books on building firearms.
Link Posted: 11/6/2001 12:34:52 PM EDT
Cut Rifling: A cutting tool is drawn down the bored barrel in a helical fashion by a rifling guide. The cutting tool cuts the grooves, leaving the lands. Every few strokes, the cutting tool is readjusted to make a slightly deeper cut until the proper depth is reached. Each groove is cut separately; very precise but time consuming. Used by Obermeyer, Lilja, and Krieger,and Shilen, among others, and can be used on any contour barrel.

Button Rifling: A carbide 'button' is drawn through the bored barrel by a hydraulic ram in a helical fashion by a rifling guide. The button swages the grooves into the barrel metal. This is very quick; it takes only about 20 seconds to rifle a 30" barrel. The barrel must be a straight contour end to end and then turned to profile after rifling. Requires a different button for each twist/caliber. Hart barrel, Spencer Barrels, among others are button rifled

Broach rifling: A broach, or graduated file, is pulled through the barrel, cutting the grooves in one pass. Not used much anymore as the tooling is fragile.

Hammer forging: An oversize bore barrel is slipped over a mandrel bearing the negative imprint of the rifling; the barrel is then literally hammered down over the mandrel by a hammering machine. The mandrel is then twisted out, leaving the bore. A popular method of producing factory tubes.

A couple of terms:

rifling guide: a cylindrical bar of metal with a helical groove corresponding to the twist rate of the barrel cut down its lenght. This indexes into a headstock on the rifling machine and controls the twist of the rifling head or button or broach as it passes down the barrel.

lands: the raised part of the rifling (duh)

grooves: what's left.

Barrel production is a very equipment intensive process. You require a deep hole drilling machine to bore the hole in the blank barrel stock, a lathe to ream to size, a rifling bench to perform the actual rifling procedure on, barrel laps, heat treat oven, to name a few. Easily a $100,000 endeavor to set up, and that's just with manual machinery. Think about that the next time you wince over a $250-$350 price tag for a premium barrel!

Enjoy!

shooter
Link Posted: 11/6/2001 4:51:02 PM EDT
Wow! Is this almost enough information, sltfshr?
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