A rifle barrel blank refers to a rifle barrel that has the bore drilled and rifled but requires fitting to the desired action before installation. This is a popular option for gunsmiths because it affords the smith maximum flexibility and control over the end product (the rifle) while outsourcing the rifling which is a very specialized machining operation that requires both expensive and specialized equipment and knowledge.
Barrel blanks come in two main categories, contoured and uncontoured. Most gunsmiths who use manual machines(see post on cnc vs manual machining) for chambering will buy contoured blanks because contouring is inefficient on most manual lathes. The exception to this is for barrels that will have integral features like sling studs, secondary recoil lugs and ribs or sight bases.
Blanks are generally differentiated by bore size, twist rate and contour. Blanks are also differentiated by the metal they are made from, 416 stainless steel or 4140 chromoly steel. Stainless barrels are usually used in accuracy applications, virtually all barrels that competitors use are stainless. Why? The very short answer is because it machines better. In addition stainless is less susceptible to rust. This is a great quality in a hunting rifle which might spend time in a damp tent or gun boot. 4140 also called chromoly steel, while traditional, is not completely obsolete however oddly because it rusts. Indeed, rusting is sometimes a good thing. Hot blue, browning and rust bluing are all controlled rusting processes. If you want one of these classic finishes on your rifle you can’t use a stainless barrel.
Selecting and ordering a blank takes some knowledge, here are some considerations when choosing a blank.
Right bore diameter for cartridge
Right contour to fit the chosen or existing stock
Right twist rate for selected cartridge and bullet weights to be used
Rifling pattern; 4 grove, 5R ect
Until next time
Ray
From left to right, a Winchester take off (finished, not a blank) Benchmark carbon fiber blank, light sendero contour, Shilen stainless #2 contour, Kreiger stainless, straight contour
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