Hammer forged vs. "std" barrels and accuracy

[Warg]

Do hammer forged barrels primarily employ polygonal rifling? Aside from higher-end match type barrels are there any appreciable differences in accuracy to be gained from hammer forged vs. "standard" (broach, button cut) AR barrels or are there other factors that play into this such as consistency of chrome lining, chamber/bore dimensions, etc? I'm not looking to win any matches at this point, just curious.

Thanks.

[Thomas M-4]

I don't know of any AR barrels that are hammer forged and have polygonal rifling.
Good article on hammer forged barrels explains the reason and benefits.
http://technology.calumet.purdue.edu...No_%207%29.htm

[BufordTJustice]

I seem to remember reading a PDF on hammer forged barrels that stated one byproduct of manufacture for hammer forging was that at least one of the edges of the lands had to rounded off in order for the hammer forging mandrel to be removed from the bore without damaging it. I know that my AK's barrel is cold hammer forged (all mil-spec AK barrels are, since cold hammer forging is the most cost effective way to mass produce a barrel) and it has both of the edges of the lands rounded off. I wouldn't say it looks identical to my G21 service weapon's barrel (which has true polygonal rifling), but it certainly is close. Lemme see if I can dig up the PDF.....

[Warg]

I don't know of any AR barrels that are hammer forged and have polygonal rifling.
Good article on hammer forged barrels explains the reason and benefits.
http://technology.calumet.purdue.edu...No_%207%29.htm

Thank you. I thought that Noveske's N4 LW barrels were HF and had polygonal rifling, but I don't have that from a reliable source.

[Thomas M-4]

Thank you. I thought that Noveske's N4 LW barrels were HF and had polygonal rifling, but I don't have that from a reliable source.

Novoske N-4 hammer forged barrels I think use conventional rifling with double thickness chrome lining. The SS barrels use the polygonal rifling.

[Miale]

i've yet to see a hammer forged barrel outshoot a cut or button rifled barrel in terms of accuracy. hammer forging is a way to make barrels quickly a cheaply and while it may be argued that there are accuracy benefits, until you start seeing them win competitions i would suggest that the jury is still out.

an unplated chf barrel will last longer than a standard button or cut rifle barrel but once you add plating there is nothing in it.

[Warg]

i've yet to see a hammer forged barrel outshoot a cut or button rifled barrel in terms of accuracy. hammer forging is a way to make barrels quickly a cheaply and while it may be argued that there are accuracy benefits, until you start seeing them win competitions i would suggest that the jury is still out.

an unplated chf barrel will last longer than a standard button or cut rifle barrel but once you add plating there is nothing in it.

That's what I thought, at least re: match-grade barrels, but don't these often have a fair amount of additional finish work involved compared to so called "mass produced" barrels?

FYI, this older post is what caused me to ask the question (see Mr Davis' response about 3/4 the way): https://www.m4carbine.net/showthread.php?t=455

[Keith E.]

i've yet to see a hammer forged barrel outshoot a cut or button rifled barrel in terms of accuracy

Aren't Steyr SSG69 barrels hammer forged?

Keith

[Thomas M-4]

Aren't Steyr SSG69 barrels hammer forged?

Keith

Yeap so does every gun manufacture in Europe if not all of them at least 90% do.

[tirod]

IIRC all pistol barrels are hammerforged, and all military Euro barrels. HK was hammerforging in the '70's.

The biggest technical advantage to hammerforging is that it doesn't leave a rough machined surface on the barrel that leads up as much. This leads to an initial advantage in accuracy as the barrel shoots from round one much like a lapped barrel, without needing extra work or expense.

Polygonal rifling is also reputed to add a small advantage in speed as it is purported to seal better with less gas bypass. It can be easier to clean, as there is no corner that is difficult to get a patch into, or harbor corrosion.

One thing to consider is that a hammerforged barrel is inherently stronger than a billet drilled and button rifled. Grain structure is controlled by being pressed into the rifling, not being cut out. For the shooter, the barrel moves around less warming up.

The recreational shooter may not do enough to see any of the results, but the militaries who specify hammerforged report fewer barrels shot out, better retained accuracy, and less cost over the life of the weapon while fielded. As more hammerforging equipment comes on line, the increased volume and less cost will become a standard, as it already is for most major firearms makers in America already.