Rifling ?

[MWnBC]

Was pondering,how is this machined in a barrel ?

When,where and who ? First time.



Mark

 

[venomballistics]

two ways to do it.
Button rifeling is done by stuffing a carbide broach down the pipe with a pile of force.
Method two is cut rifeling
this is similar to turning internal threads on a lathe

 

[venomballistics]

oh yeah ... and leave it to the Germans to hammer forge a barrel on a rifled mandrel as was done for the MG 42

 

[OKFC05]

When,where and who ? First time.

Step into the wayback machine with Mr Peabody........

Like the first use of gunpowder in a tube to shoot a bullet, we really don't know when rifling began. It is know that from an early time, grooves were cut to try to deal with blackpowder fouling, and somebody discovered that grooves cut at an angle stabilized the bullet.
Rifling was well known and used in hunting guns even when armies still used smoothbore flintlock muskets to allow faster loading.
The famous PA and KY long rifles were not invented here, but adapted from the German Jaeger or hunting flintlocks.

 

[Scrapper]

Here's a good link to read on making rifled barrels

The Making of a Rifled Barrel, FirearmsID.com

Here's a bit of that web page:

Of all the elements that make up the rifle it is the barrel that seems to hold the greatest mystique and mystery. Anybody with rudimentary knowledge of engineering practice could see vaguely how to make the action. Anybody with a lathe, a milling machine and the usual tooling of a small workshop - and the knowledge to use them - could make a bolt action.

But the barrel, that is a different matter. How do you drill such a long straight hole to form the bore? How is the rifling put in? How is the shiny finish in the barrel achieved? And above all, what is that special something that differentiates a so-so barrel from a hummer?
Each operation in the making of a rifle barrel requires a special machine tool rarely found outside a barrel shop. That said, there is no real mystery in making good rifle barrels. But it does take care and attention to detail. In this article I will outline the main processes involved in turning a bar of steel into a rifled barrel, indicating where barrel makers differ in their approach.

The United States is the home of the custom barrel maker and there are literally hundreds of small barrels shops up and down the country - some still using unbelievably primitive equipment - who make barrels to the customers specifications. There are also some very large barrel makers who make barrels primarily for the trade. The common denominator is that making barrels is all they do. Very little of the turnover of these barrel makers comes from making actions or rifles or doing other gunsmithing. This picture contrasts very markedly with the rest of the world - except Australia where a country of 15 million population supports at least three barrel makers!

Europe, with a population approaching three quarters of a billion has less than ten barrel makers, of whom only one is a "small" custom shop. Unlike the United States, the European tradition is that a rifle manufacturer will make everything in house and not subcontract to specialist manufacturers. There are exceptions such as Lothar Walther in Germany and Unique in France, who occupy the position of Douglas or Wilson Arms in the U.S. supplying barrels in quantity to the trade and also to the retail public. Great Britain, once the home of a vast gun trade centered in London and Birmingham, now only has two barrel makers outside the ordnance industries.


PRATT & WHITNEY HYDRAULIC RIFLING MACHINE

CUT RIFLING.

"Cut rifling is a real hard way to go. I can't think why anyone should go that route." - I forget the name of the Australian reloading tool maker who made this observation, but there have been times when I have heartily agreed with him!

There are currently three main methods by which rifling is put into the barrel. By far the oldest method, invented in Nuremberg in around 1492, is the cut rifling technique. Cut rifling creates spiral grooves in the barrel by removing steel using some form of cutter.
In its traditional form, cut rifling may be described as a single point broaching system using a "hook" cutter. The cutter rests in the cutter box, a hardened steel cylinder made so it will just fit the reamed barrel blank and which also contains the cutter raising mechanism.

The cutter box is mounted on a long steel tube, through which coolant oil is pumped, and which pulls the cutter box through the barrel to cut the groove. As it is pulled through it is also rotated at a predetermined rate to give the necessary rifling twist. A passing cut is made down each groove sequentially and each cut removes only about one ten thousandth of an inch from the groove depth.

After each passing cut the barrel is indexed around so that the next groove is presented for its passing cut. After each index cycle the cutter is raised incrementally to cut a ten thousandth deeper on the next cycle, this process being continued until the desired groove diameter is reached. It takes upwards of an hour to finish rifling a barrel by this method.

The rifling machines found in custom barrel shops are invariably Pratt & Whitney machines. For the first world war some thousands of "Sine Bar" riflers, so called because a sine bar is used to determine the rate of twist, were built to satisfy the demand for barrels at that time. These belt driven single spindle machines weighed about a ton and were suitable for the wooden floored workshops of that era. After WW1 many of these machines became available quite cheaply on the surplus market and so in the inter-war years these were the standard rifling machine in barrel shops across the World.

RIFLING "HOOK" CUTTER.
The heart of the cut rifling method, making and
maintaining these cutters require great skill.

 

[Alk8944]

Cut Rifling: Single cutter, multiple passes, either scrape or hook cutter.

Broach Cut Rifling: Cut rifling using a multi-step cutter, reverse image of rifling, cuts all grooves in one pass as the broach is pulled through the barrel.

Button Rifling: A Carbide button shaped as a reverse image of the rifling but smooth is pulled or pushed through the barrel in one pass literally pressing the rifling grooves into the steel. his can be done mechanically, hydraulically, or even by literally firing the button down the reamed barrel blank like a bullet.

Hammer Forged Rifling: Barrel blank is hammer forged around an arbor which bears a reverse image of rifling. Doesn't require the blank be drilled and precisely reamed. Probably the most common current method used by major manufacturers today due to speed of the process.

Electrical Discharge Machining: An electrode formed to the contour of the desired rifling is passed down the drilled barrel blank in an oil bath. An electrical current erodes the steel to match the shape of the electrode while it is in the barrel. This is the current method used by S&W. Biggest advantage is speed, smoothness. Should be no reamer marks or chatter as with some methods. Depth of rifling controlled (sometimes not very well!)* by strength of current and time.

*I include the "not very well" remark due to a .44 Mountain Gun I had that was an early EDM gun. It had a groove diameter of .435, throats .429. Charge holes were not large enough to use a .435 bullet (after reaming throats) without reaming the cartridge cases first. Had to special order neck reamer from Forster to ream the cases. Lapped a Lyman 429421 so it would throw bullets large enough. Shot very well after all the problems, but it was a real PITA to feed so I sold it, and have never regretted it a bit!

 

[LVSteve]

EDM is the latest thing but some folk do not like the way the rifling is not razor sharp at the edges. The lands look a little like those on an Enfield rifle, which given the way many Enfields shoot is not necessarily a bad thing.

 

[Scrapper]

Alk8944 mentioned the button tool.

I almost forgot there was also the method of firing the tool, with rifling formed into it, down the barrel.