Pistol Barrel Manufacture

[Jim Watson]

In a closed thread, we read

"Let's take the examination to another part - barrels. It's apparently not common knowledge the vast majority of barrels in American rifles and pistols are all cold hammer forged, and have been for some time. No, diligent workers are not setting up button rifling or scratching grooves in drilled blanks to make your gun. One guy loads a pallet of short fat tubes and the machine pounds the snot out of it forcing the lands and grooves into it."

I know that hammer forging is a common process for mass produced rifle barrels which are of circular cross section.

However, it has been my perception that the process was not readily adaptable to asymmetrical shapes like pistol barrels with their locking lugs, camming lugs, link lugs, etc.
Have the manufacturers beaten that limitation?

 

[rskent]

My understanding is that you cold hammer forge the blanks, stress relieve them, then machine the outside last.
The square (ish) chamber end or lugs shouldn't make much difference.

 

[Drail]

Some manufacturers like S&W have switched to electro discharge machining with polygonal rifling (around 1996) which works fine with jacketed slugs but not so fine with cast slugs.

 

[Tirod]

Last paragraph: http://firearmshistory.blogspot.com/2010/05/rifling-manufacturing-hammer-forged.html

I think the comment on manufacturing processes being a "black art" has more to do with those hammer forged barrel makers selling their product to any purchaser, ie a Ruger or S&W could have the some subcontractor.

So how does one gun shoot better than another? Goes to each individual recipe of alloy, shape, etc and then how the barrel fits into that gun thru the makers unique view of the Browning lock up system.

It was brought up in threads on hammer forged vs button rifled in AR forums years ago. It's still an ongoing conversation. HK was using hammer forged and nitride polygonal rifling in their G3's and HK91's back in the '70s. But - the milspec for the M16 is button rifled and chromed to this day AFAIK. Goes to milspec not being a reflection of current advanced methods, just an inspectable criteria to protect the tax payer.

It raises the question that if FN is hammer forging M16 barrels are they now being accepted? It's not common knowledge in the shooting community. We seem to be getting some of the memos, tho, nitro carburizing and MIM are starting to be recognized as methods of manufacture. It just takes the average American shooter about 25-40 years to catch up. Tradition runs deeper in their knowledge base than it does in reality.

 

[jmorris]

Springfield used (might still) 2 part barrels in their 1911's if you google you can find photos of them where they seperated.

I don't know how many use hammer forged barrels but I know that there are still cut rifling barrels out there for sure.

 

[Tirod]

The Kahr .380 series guns use both. The P series is the hammer forged polygonal rifling, the CW series uses a conventional cut or button bore.

The significant difference in price may be due to the older method being "paid for" in terms of tooling and the ability to run smaller batches competitively priced. A $1 million dollar barrel forging machine has to put out a large number of barrels to get the price down.

If I remember the conversations correctly all the major gun makers in the US have or use a hammer forging machine for the bulk of their pistol production, and for most of the commodity rifle barrels for hunting guns. Most of the high end precision barrels are not and will continue to be cut or button rifled.

Because of the American consumer's prejudices and basic lack of education in production processes most of this isn't openly discussed. A hammer forged nitride barrel is only as good as the mandrel it's produced on, a cut/button rifled barrel only as good as the tooling and expertise of the barrel maker. Each has it's strengths and weaknesses and the makers apply the process which produces a good part for the most economical price.

Goes to the Glock, too, and it's polygonal rifling which doesn't handle bare lead projectiles well under warranty. They've been in service since '82 - over 34 years - with a hammer forged barrel. It's the American market and demand to shoot cast bullets in handloads that has created a market for a broached barrel.

34 years of production and the American shooting public is still getting up to speed on how guns are made. Same for buyers of Swiss made watches - tell them they were robotically assembled by the thousands daily and you undermine their expectations of "superlative quality" and "hand craftsmanship."

Gun ownership plucks a lot of heartstrings and the makers enjoy playing tunes that support buyer loyalty. So discussing the rudiments of how they are made doesn't contribute to the romance.

 

[Jim Watson]

A $1 million dollar barrel forging machine has to put out a large number of barrels to get the price down.

I read an article - American Rifleman, maybe - that said when Ruger bought a hammer forge machine, it sat idle for some time before it became economic for them to make their own instead of buying button rifled barrels from an outside supplier.

They must be doing good stress relief. Early Steyr Mannlicher just buffed up the hammer mark and sent them out the door. Advertising or not cutting stressed metal?

 

[BWB]

C'mon folks. There is a lot of misinformation here. All the manufacturing processes CAN and do produce high quality barrels. The choice has more to do with the volume and efficiency and capital investment involved. Have you priced a hammer forging machine lately? You'd better be making barrels by the rail car load. If you are, it's the way to go.
Cut rifled, button, and EDM are capabilities available to the small to mid volume custom maker, so that's what they use to produce their barrels. The difference is care, attention to detail, hand or machine lapping, etc., not mojo in the process itself.
The major pistol/revolver makers do not source their barrels from vendors, so they are not the same. Many if not most lugged barrels are produced from forged blanks and rifled on broaching machines.
Most all manufacturing processes are based on starting with a blank as close as possible to the finished shape produced by casting, forging, or bar stock, to reduce to a minimum machining cost and waste on the way to a finished product that meets the spec's.

 

[Jim Watson]

The last I read, S&W broached and lapped conventional revolver barrels, ECM rifled the monster magnums.
Their two pice barrels could be buttoned or hammer forged, rifled by the yard, cut off 4" at a time. But I don't know for sure.
The two piece Springfield and Brownings could be made that way, too.

 

[jleonard]

I think the comment on manufacturing processes being a "black art" has more to do with those hammer forged barrel makers selling their product to any purchaser

"Black Art" would apply in my opinion. As a manufacturing engineer I worked with this process for many years not in barrel manufacturing but making automotive steering and suspension parts. Depending on materials and configuration (lengths, shapes etc) there can be a significant development process to get it right. Experience is key and a little change in material (steel lots) tool wear etc can dictate the need for "adjustments". Knowing how much to tweak when is where the black art knowledge comes in.
And none of our machines cost as much as the article claimed.

 

[YankeeFlyr]

Never heard of EDM for gun barrels, although I've designed machine parts that were made using that process (years ago)...

 

[BWB]

I haven't either. My reference to EDM was a mistake - missed key stroke and failure to proof read. It is of course ECM.

 

[tonyjr]

To me a rifled barrel is better . I have reached the point where all I reload is jacketed bullets . More accurate and seem to shoot flatter .
If you hot load lead / cast bullets they can and do fall apart in air .