help understand a few rifling types

[cs86]

I've noticed a few things in newer guns that I've purchased as far as the rifling goes and was hoping to get a little better understanding. Primarily focusing on land and groove rifling and how it is formed.

Button rifling for lands and grooves appears to be the most common type. Is this correct? Then there is hammer forged. The Springfield pistols that I have are hammer forged rifling from my understanding. Then there are some rifles that I have that are button rifled. When looking down the bore of the hammer forged rifling the bore looks like a pristine shinny bore that is real smooth. Then I've looked down some barrels and notice something different on the button rifling. If I get the light right and look more at the muzzle end I can notice something in my best description as tooling marks. Like faint rings running down the barrel. I'm assuming after running several jacketed bullets down a barrel that it would smooth this down. Is this more common then not in button rifled barrels? Do better manufacturing practices lap the barrels to smooth out these tooling marks or is there different practices that they use to create a quality bore?

Please excuse anything that may not make sense. I'm new to the subject and could use some education. I've noticed 3 barrels of different calibers that I've noticed having the distinct markings.

[Smoke4320]

Button rifled barrels are going to have some tooling marks as the button is drawn thru the tube to create the rifling ..
hammer forged means the mandrel is inserted in the tube and then a machine using multiple hammers to create the rifling .. As long as the mandrel is in good shape it will produce a smoother rifling.. Also hammer forging reduces grain size in the steel thus in theory a longer lasting barrel

[largom]

In my experience only custom barrels are lapped, factory barrels never. I fire-lap all of my guns.

Larry

[mdi]

To add a bit to Smoke's post; the mandrel for hammer forging has the "positive" rifling machined into it and the hammers pound the barrel metal down around the mandrel and the barrel ID is formed into the mandrel creating the rifling...

[btroj]

Here Ya go, read up.

http://www.firearmsid.com/feature%20articles/rifledbarrelmanuf/barrelmanufacture.htm

always remember, GIYF

[Ballistics in Scotland]

Here Ya go, read up.

http://www.firearmsid.com/feature%20articles/rifledbarrelmanuf/barrelmanufacture.htm

always remember, GIYF

That is a priceless link, for which much thanks. I've seen it before, on Dr.Kolbe's Border Barrels site. I doubt if his barrels are worth the cost and trouble of importing, except for people living where nobody makes quality barrel blanks. But I know people who use them, and I'm sure they are as good as any. I think one of them was used by a friend of mine to make a British record, a group fractionally under 4in. at a thousand yards, with a rifle which wasn't at all unconventional in design.

I am sure nobody has proven any consistent superiority in accuracy for any of the means by which barrels for the enthusiast are currently made. The toolmarks from button rifling are in line with the rifling, which isn't a problem. Where cut rifling does score, however, is in rerifling a bored-out barrel, or in rifling a blank which already has a tapered profile. Barrel steel has quite a bit of elasticity, especially after work-hardening, so it is liable to spring back from either the button or hammer processes - and spring back differently according to whether it is thick or thin. These processes are best kept for barrels which are the same diameter from one end to the other, and are profiled afterwards.

It you take a large hammer and smite the end of a metal bar held in a vice, you will shorten and expand it for the upper part of its length. If you use a light hammer with greater velocity, you may deliver the same energy, but the bar will be rather more nail-shaped, expanded immediately adjacent to the top. I don't know how deep the work-hardened zone from hammer-rifling goes, but it could easily be for all or most of the thickness at the thin end, and only part of it at the thick end. I don't know which I mistrust most, turning down that barrel, or leaving it with the little spiral dimples of hammer-rifling all over, as Steyr used to do.

There is another process we seldom see mentioned, and that is broaching. In some ways it is akin to button-rifling, but a steel tool has, for each groove, a series of teeth increasing in diameter, so that the rifling is cut in one pass. This was chiefly used for military barrels, and as carbide is brittle, it may be that they never changed to it. I think this is responsible for the oversize groove diameters of, for example, some No4 Lee-Enfields. If they started with the largest diameter broach they could get away with (and how big that is depends on how a potential enemy, known hypothetically as Germany, is behaving), you get the maximum number of sharpenings out of it before it has to be discarded. I wouldn't be surprised if some obscure British warehouse is still stacked with broaches just a little too small for a .303.

[DR Owl Creek]

Here's another link to an interesting article on barrels. It's from the benchrest shooting perspective, but most of the info such as the types of steel used, contour, twist rates, types of rifling, number of grooves, fouling, fluting, etc., would apply to the cast bullet world as well:
http://www.6mmbr.com/barrelFAQ.html

Dave

[Scharfschuetze]

Reading those articles brought back some fine memories.

Back in the early 70s I was stationed in Texas and worked part time for a gun shop in Killeen. The gunsmithing was done at a little shop and range south of town and that's where I worked. I helped drill, button rifle and contour barrels as part of my duties there. I made my own rifle and made everything except the action (Gew 98) and sights (Lyman).

Later on, I was able to watch Richard Hoch make his cut rifled barrels in his shop in Montrose, Colorado. I still use one of his nose pour moulds.

It was all quite an adventure for a young shooter.

[M-Tecs]

Broach rifling was very common through WW2 and ECM (Elecrto Chemical Machining) and EDM (Electric Discharge Machining) are getting more common. S&W uses ECM

Electro Chemical Machining
http://firearmshistory.blogspot.com/2010/05/rifling-manufacturing-electro-chemical.html (http://firearmshistory.blogspot.com/2010/05/rifling-manufacturing-electro-chemical.html)

Electric Discharge Machining
http://firearmshistory.blogspot.com/2010/05/rifling-manufacturing-electric.html (http://firearmshistory.blogspot.com/2010/05/rifling-manufacturing-electric.html)