Another Barrel Breakin Thread

[Scorch]

The long steel bar stock was hardened and tempered before any work was done.

Hammer forging does not start with bar stock, it starts with tubing or a steel spud that has a hole drilled in it for the bore-shaped mandrel that will be the bore and rifling once the barrel is finished. In "cold hammer forging" the hammers rotate around the axis of the spud and hammer on the barrel material, forcing it down to the mandrel and impressing the rifling on the inner surface of the tube formed as the metal is displaced along the mandrel. The material gets quite warm as this is happening, and the metal is pushed and shaped. The interior finish on the bore and grooves is quite smooth to the eye (borescoping shows otherwise) and is stress-hardened due to the hammers' action. These barrels are typically straightened before use.
http://www.lasc.us/RangingShotBarrelMakingFeature.htm

Hammer-forging was first used in making barrels in the late 1930s for German military weapons, and was in use for many years prior to civilian market introduction. Hammer forged barrels were introduced to the US markets by Sako in the 1960s.

Traditional barelmaking starts with annealed and stress relieved bar stock which is then deep hole drilled, reamed, stress relieved, sometimes honed, and then the rifling of the bore begins, either by cutting or by pulling a carbide plug through the bore to form the rifling.

They all may not stress relieve them after hammer forging but they should...

Due to the large amounts of stress imposed on the barrel tubes, stress relieving would cause warping which would actually add handwork to the barrel production process, and industrial processes are designed to eliminate handwork from processes.

 

[warbirdlover]

Hammer forging does not start with bar stock, it starts with tubing or a steel spud that has a hole drilled in it for the bore-shaped mandrel that will be the bore and rifling once the barrel is finished.

Yes it DOES start with bar stock. Tubing is made by welding and is unacceptable for barrels as there is a weak spot. They take a bar, heat treat it, "gun" drill it (you'll have to look that up) and THEN hammer it around a mandrel. How do I know? This is how heavy duty shafts are made.

And I mentioned a video which showed the bar stock. And your attached link describes taking bar stock and drilling it. It then has the mandrel put down the drilled bore and numerous hammers pound the outside of the bar to conform it to the rifling on the mandrel. The mandrel is removed and the bore is sometimes done or sometimes lapped.

And if the operations put stress in the barrel wouldn't you want it stress relieved (which causes warping) and after that straightening of the barrel? (They have automatic "sraightening machines" now.) If you don't the stresses in the barrel WILL be relieved when you heat the barrel up from shooting. THEN it warps and now what have you got?

I'm a retired metallurgist who also was a manufacturing engineer in a transmission plant. I've developed processes for many kinds of parts so am not BS'ing you.

No matter what the method of putting in the rifling, hammer forging, cut, or button rifled the barrel starts as bar stock and then is rifle or gun drilled. And this bar stock is pre-hardened and tempered to HRC 32-40. I've been through the Hy-Alloy bar stock plant in Indiana where we bought our bars from many times and the furnaces used are continuous with one bar after another going through. There is a (intensive) quenching "ring" which hardens the bar using water and it goes immediately to the tempering furnace in line. It's pretty impressive to see.

http://www.riflebarrels.com/articles/barrel_making/making_rifle_barrel.htm

 

[old roper]

here something on barrels

http://www.border-barrels.com/articles/bmart.htm

http://obermeyerbarrels.com/steel.html

 

[Art Eatman]

Just shooting burnishes a barrel. Back in the 1930s it wasn't uncommon to run lead bullets through a bore in the burnishing process, although this seemed mostly to be the dedicated target shooters.

I got into centerfire in 1950. Until I came to TFL in 1998, I'd never heard of all this "barrel break-in". However, I, my uncle, my father and multitudes of shooters had somehow managed quite a few sub-MOA groups without ever going through all this breaking in.

Seems to me, just offhand, that the only rifles for which it would be a benefit would be those of sub-standard production. Some folks have posted here that they found that the break-in made it easier to push a cleaning patch through the bore. Seems to me that it indicates a rough barrel to begin with. So far, I've never had that problem...

 

[HKFan9]

I have plenty of Sub-MOA rifles by different mfg's and I have never done a barrel break in.

Generally I just bore sight it.. sight it in... blow through a few boxes of cheap ammo... either Rem Core-lokt, or Federal power shock. Then I just take the brass and start handloading.

My current favorite bolt gun is a Rem. 700 Tactical in 6.8SPC. With 110gr SMK handloads right now I have consistant 1/2 MOA groups... the best group being 3/8's MOA.

I just got a Sinclair Concentricity gauge for Xmas... so hopefully I can shrink my groups down after batching the bullets, brass, and final loads.

These reloads are still in the crude phase as well... I have not done everything I can to squeeze every bit of accuracy out of them, such as annealing, or even weighing and batching the the bullets.

For me.. I think it is a myth. I have owned sub moa rifles by Rem. Ruger Savage, Sako, to name a few... and I never went out of my way to break in a barrel.

Also, it generally takes me 3 shots to walk a shot in while sighting in for the first time... then once I am in the bullseye, I will shoot another 3-shot group. I have right after sight in, printed sub MOA groups... so that would be 6 shots from me... and lets say 1 to 3 shots test fired in the factory. That would give me a total of 7 to 9 shots fired total, with no cleaning in between, that prints Sub-MOA at 100yards. To me that disproves barrel break in procedures. To each his own I suppose.

I can't tell you how many customers we get back stating the rifle does not group right... and when we go and test fire them, they print fine. Most error occurs behind the trigger.