To start, we will discuss what barrel contour is. You may have noticed that barrels range in shape, size, weight and profile. This can be for many reasons but one of the most common reasons you may see a contoured barrel is to cut the weight of a rifle down. A good example of this can be found on a variety of AR-15 rifles. Some states require that it come with a heavy barrel that keeps the same profile from bore to muzzle but these often weigh a lot more. Other states don’t have such restrictions and will allow the AR-15 to be built with barrels that have much less material that weigh less and cool off much faster after use. The term barrel turning commonly refers to a gunsmith taking a blank of metal and chucking it into a lathe in order to machine off the excess metal and create the profile or contour they want.
To do this, you may want to use a bar of heat-treated steel for a lathe center. It is at this point that you may also want to face off or remove 1” from the muzzle end because the end may be flared from the boar reaming process. Now for this next step, the cutting tool used will vary from shop to shop but a slightly dull tool will cut far better than a sharp one in this case and the speed at which you run your lathe may depend on how the metal is supported. One method of barrel turning has you remove the center all together and chuck the barrel directly into the 3-jaw. The blank will then be turned in sections making your cuts close to the chuck and moving the blank multiple times. Hogging off large amounts of material should be done in steps as well and not to be done all at once. Work one side then flip it in the chuck to hit the other side allowing time for the other half to cool while the opposite half is being worked. The type of tools used to work the barrel and the process you use to achieve this are going to change depending on the type of metal used. Finally, once you have a relative size and shape you can complete your final turning using a fine feed and a light cut. This is the final step so please take your time and be sure not to damage your final product.
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