Mini 14 are Hammered Forged Barrels and last a real long time.
Hammer Forging
Again, it was the demands of war that was responsible for the development of this process - only it was done by the other side. Hammer forging was developed in Germany in 1939. Here a drilled barrel, rather than being reamed, is honed to give it a very fine interior finish. Then it is placed on a tungsten carbide mandrel that has the entire rifling pattern ground in relief into its surface. The barrel/mandrel combo is then placed between two opposing power hammers and rotated. The hammers literally beat the barrel into the mandrel’s pattern. I’m told a barrel will actually grow around a third of its length during this process. It usually takes around three minutes for the rifling process to be completed. As you would think, this method produces tremendous stresses in the barrel that have to be relieved through heat treating.
The advantages of hammer forging is the fact that the interior finish is very good, and the bore surface becomes work hardened in the beating process. The result is a very durable, long lasting barrel. Modern hammer forging has progressed to the point that even the chamber can be included in the mandrel pattern. These machines are very large, complex, and expensive however. So the small custom barrel shops are pretty much eliminated from using them.
Additionally, some say that the induced stresses are so severe in this process that they never can be entirely eliminated. As a result, the bench rest crowd won’t touch a hammer forged barrel. However, I can’t help but wonder how valid this belief actually is, and whether anyone has actually tried it. Remington barrels, which always had a reputation for accuracy, used to be hammer forged, including those used in the XP-100. I know I always had excellent results with original XP barrels. Indeed, in Europe, hammer forging is the standard. Sako, Tika, H&K, Steyer, and Sauer all use hammer forged barrels. I’d hardly call their products junk.
http://www.lasc.us/RangingShotBarrelMakingFeature.htm