The UK's Finest Independent Forum for Shooters and Gun Owners. Est 2010.

meles meles wrote:ooh, a zombie thread...

Yes, hammer forged barrels are made by hammering them over a mandrel until they take up the form of the mandrel. The process is quick and, once the cost of the equipment has been borne, relatively cheap. For this reason, hammer forged barrels are often used for military rifles where large quantities of moderate to high quality barrels are required at reasonable cost.

A properly made hammer forged barrel made over a good mandrel can be of exceptionally high quality. If care is taken, and the mandrel carefully used, the possibility of having cuts, burs and scratches is virtually zero. With the correct post processing, there will be fewer problems arising from stress within the barrel. In addition, the use of a mandrel allows for quite tight tolerances on the rifling twist and form, and such things as progressive rifling are easier to make in this manner than by cutting or button rifling.

That said, there is no one process that is best. Carefully executed, all will produce good barrels. Hammer forged can be the lowest cost, and potentially the highest quality. I believe Tikka / Sako use hammer forged barrels on most of their rifles which is perhaps good testimony to the cost / quality ratio.

R.G.C wrote: Sorry to be controversial here.

meles meles wrote:

R.G.C wrote: Sorry to be controversial here.

No need to apologise ooman, almost all opinions are welcome here. We merely gave our opinion as a small brained creature, albeit with a degree or two in metallurgy and stress engineering, and pointed out that all the processes mentioned can produce excellent barrels when properly executed. We're not saying hammer forged barrels are better, simply fighting their corner and pointing that they can be...

We agree that hammer forging generates stresses, more so than a machining process, which is what cutting or buttoning are. However, as we mentioned, proper post forging heat treatment can resolve those issues and then you are left with a forged barrel. Forging is an excellent process for grain refinement and stress engineering: think about the crankshaft in an engine - there's a very good reason why its forged and not machined. Off the top of my, admittedly small, head, I can't think of a single example of a crankshaft made by machining it from the solid.

Yes, hammer forged barrels can be harder than machined (ie cut or buttoned) barrels. However, in the great scheme of things, the hardness levels involved aren't that hard in true engineering terms. Any engineering shop with decent modern cutting tools will have no problems with them. An alternative for those too backward to buy modern tools would be to specify the post forging heat treatment to partially anneal the barrel down to the levels commensurate with their tooling technology. Of course, you'd then have a barrel that wore faster, was more prone to corrosion and so forth...

In the sett armoury are examples of rifles with button and hammer forged barrels. We wouldn't be averse to owning a cut barrel if we had deeper pockets. Each of our rifles is capable of greater accuracy than we can attain with them, hence squeezing out the last quintilliard of performance from them is a redundant notion. Purely on metallurgical principles we'd opt for a properly made hammer forged barrel over any other. That's our choice, your mileage may vary and shots can go down as well as up.

R.G.C wrote:

meles meles wrote:ooh, a zombie thread...

Yes, hammer forged barrels are made by hammering them over a mandrel until they take up the form of the mandrel. The process is quick and, once the cost of the equipment has been borne, relatively cheap. For this reason, hammer forged barrels are often used for military rifles where large quantities of moderate to high quality barrels are required at reasonable cost.

A properly made hammer forged barrel made over a good mandrel can be of exceptionally high quality. If care is taken, and the mandrel carefully used, the possibility of having cuts, burs and scratches is virtually zero. With the correct post processing, there will be fewer problems arising from stress within the barrel. In addition, the use of a mandrel allows for quite tight tolerances on the rifling twist and form, and such things as progressive rifling are easier to make in this manner than by cutting or button rifling.

That said, there is no one process that is best. Carefully executed, all will produce good barrels. Hammer forged can be the lowest cost, and potentially the highest quality. I believe Tikka / Sako use hammer forged barrels on most of their rifles which is perhaps good testimony to the cost / quality ratio.

I would by no means make the confusion between a (hot) forged crankshaft and a cold hammered (not forged, improper not profssional term) barrel.....

There had been even cast crankshafts but I do not think there has ever been cast barrels?.

Have you even seen how a crankshaft 'lopin' ( perhaps 'billet' in English would be the right translation, not sure) looks like?.
R.G.C


Sorry to be controversial here.

It happens I have seen the hammering process in Suhl time ago (1993-94 I think) and have worked on hammered CrMo barrels made there by this process.

Hammering, starting from a blank of about 300mm long 50mm OD to end at a, say, middle Palma profile 760mm long generates much more stresses than conventional machining or even buttoning.

More over, the temparature rise need allowance for the dilatation, which also helps the mandrel to slide out from the finished barrel (I assume the mandrel could not be removed if the barrel would have benn allowed to cool down at ambient temperature. Dilatation is certainly the less predictable dimensionally.

On question of progerssive twist, Suhl claimed they could do it, but I must wonder how a progressive-twisted mandrel could be 'screwed out' of a progerssive pitch barrel rifling???.

Finally, barrel hammer forged are VERY HARD and this hardness makes cutting chambers and thoats very difficult to be cut to the accuracy to our actual standards..... Most of mass production barrels are hammered with mandrels making same time chambers and throuats and therefore, those chambers and thoats ends to fixed dimansions of quite generous tolerances.

Firms like Steyr (who now also owns Suhl) having the capacity to hammer forge harrels for thier military products naturallt use it for their cicilian production, but I think the geralisation of the pricess will remain imited to that for a while.

BTW, Steyr-Daimler-Puch even does not thread their barrels who are also crimped in their actions. This saves an other machining operation with the lack of adjustment possibilities it implies.

All in all, the experience made at this time by a friend with hammer forged barrsls was not very conclusive.

R.G.C

meles meles wrote:For several hundred years casting was the primary, indeed for a while only, means of making gun barrels. They gave up on it as technology advanced and the bell foundrys went back to founding bells.

With regards to the correct terminology, hammering the barrel is most definitely forging. At least it is deemed so in the Metallurgy Departments of the Universities of Cambridge and Sheffield. However, if its says otherwise somewhere on t'interweb I am sure both those august institutions will cede the point and, though I have never been taught at MIT, the third recognised authority on the subject, I suspect they too would acquiesce to the new wisdom. As for any temperature influence, the barrel may begin cold but adiabatic shear quickly warms things up. You can prove this to yourself quite easily with scientific equipment no more complex than a hammer and a piece of metal if you choose to disregard your own previous comments about heat induced dilatation.

R.G.C wrote:
I have for principle to never extend an agressive argument of that kind in a foreign language...Conclude as you will.....

R.G.C