what is it
idk why they'd need/want action or bolt though
I prefer to have the action because if it is a straight flute, we like to index/time the flute to the "north pole" so that it presents well when assembled. Even with helical fluting, it is nice to see the start/end of a flute land at 12 o'clock.
Fluting is all about
"if it looks right, it is right."
As for the age-old debate regarding fluting, stress, harmonic, and other buzzwords:
My analogy is a ball of rubber bands. Attack it with a pair of scissors, and you're left with a pile that resembles nothing like a ball. Take the same ball and toss it in an oven for a while that is hot enough to remove most of the tension/elasticity without destroying the rubber by setting it on fire. It's not quite a ball when you are done, but it's sort of in the neighborhood of the original shape.
The point here is when you cut, machine, grind, or basically "anything" on a piece of material, you are
removing* stress.
*
The assumption is made that were observing good machining practices. Sharp tools, speeds/feeds appropriate for the materials, etc... It is very likely/possible to work harden certain steels if this is ignored, which will create its own set of problems.
The first process with the scissors describes a machining process. The stress of the bands being stretched over one another has been removed by cutting away material. Anyone who has fooled around with a face mill and chewed on a bar of material has discovered that once you pull it from the vise, the piece will bow up like a cat does when you pet it.
The oven process is normalizing. The intent is to remove/reduce all the "inner turmoil" that a piece of material is riddled with as a byproduct of producing the basic shape. When you do this first and follow up with various machining operations, the likelihood of it taking off, distorting, and creating a series of cascading problems is reduced. How well this works depends on the material you start with. Fortunately, barrels are typically made from good-quality steel. Hammer-forged stuff can be a little fussy, but that process is almost entirely exclusive to mass-produced box store guns.
My experience with fluting is that if you use good tools and have a machining strategy that makes sense, the likelihood of cutting on the steel and somehow ruining how the barrel shoots are quite small. The "Pattern X" stuff we do is about as invasive a process as anyone has ever done to a gun barrel. We pull
pounds of weight out of stuff when we do that for folks. Rest assured, if it was a hot mess, the internet would tell you, and my phone would blow up about it.
To my knowledge, there is not a single barrel manufacturer that makes a barrel by contouring, fluting, drilling, reaming, and then producing the "wrinkles" down the hole. It would be a nightmare to set up a contoured stick of material in a gun drill and rifling machine. Whether you buy a barrel from brand X with flutes or have someone like me do it, I can say with almost 100% certainty that the machining process for the flutes is done as the last step.
The reason I started doing it is that I despise having to fit a fluted barrel to an action. Having something look right is just as important to me as its functionality. Clocking a flute on a lathe is not a trivial task. The resolution of a healthy human eye is about .003" of an inch. If you can see the thickness of notebook paper, you have that ability. Barrels commonly have a 1.250" diameter cylinder up by the receiver face. .003" is equal to .275 degrees or 990 arc seconds. If I want a fluted barrel to appear "timed" to the receiver, I need to get within about a .006" range in terms of clock position. A little over half of a degree. On a receiver using a 16-pitch thread, a degree's worth of rotation equates to .00017" worth of linear travel along the pitch. Split that in half, and you get into something approaching the half-degree we have with healthy eyesight.
.00017" is a human hair split roughly 17 times. You will not whisker that small of a cut off the shoulder of a barrel in a lathe. You might be able to carefully sand a recoil lug with something absurd (1200grit) with a swipe or two and get there, but even reliably measuring it afterward is not going to be easy. Now, factor in all the variables.
- How's the thread fitment between the barrel/receiver?
- How much and what thread lubricant is being used when it's all put together?
- How repeatable is the torque wrench?
- What about thread crush? (A freshly machined thread will yield slightly the first few times it is tightened/loosened, causing the clock position to change slightly.
- Is there any hint of a rolled/raised edge at the face of the shoulder where it meets the contour? It will influence the clock position as well.
The process I adopted a long time ago was to start with a conventional blank/contour and focus the lathe work on getting the fundamentals handled. Tennon length, thread fit, breech clearance, and headspace. Mock the thing up and get the threads "set" by torquing it on/off a few times. Check the HS one last time to ensure it didn't suck up from the shoulder and threads yielding slightly. Then set it one last time to index the top using the front scope base hole and a small punch aimed at the root of an exposed tennon thread visible through the base hole.
Now pull it back apart and move forward with the fluting process.
As for the "harmonic word", nodes, etc. . .
I challenge anyone to walk into a barrel company's facility, randomly select a barrel off the rack, and be able to accurately state what the seating depth, charge weight, and all the other reloading variables will need to be for that barrel to deliver its full potential. We don't know, and there's no way to guess. We can start with an educated hunch, but testing and evaluation is the only way to qualify and realize where it will ultimately land. Whether the barrel is fluted or not doesn't somehow change how you do the ammo prep.
If your existing rifle is performing well and you have the barrel fluted,
plan on having to alter your reloading strategy. The mass of the object (barrel) changed. It stands to reason that frequency and amplitude changed as well. Playing around with charge weights and seating depths has as much to do with finding the "dead spot" where the bullet leaves the crown simultaneously to the barrel, becoming motionless for a split second as it does, achieving a stable/repeatable velocity average.
Hope this helps.
C.