To flute or not to flute? That is the question.

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Some of you machinist types out there may know this.

Do you know what happens when you machine a groove into a steel rod or bar?

Well???? I don't know either. That's the problem. It will deform in an unpredictable manner due to relieving internal stresses in the stock material.

It's a mystery to me that fluted barrels shoot as well as some do. If flutes are shallow then there would be less tendency for deflection but I certainly can't guess what that amount would be. I'm not a big fan of fluted barrels.
 
Browningguy...

Varmint Al made a nice try at explaining things but he got some of his wording wrong. One place he says that fluting doesn't have any positive effect on accuracy, then he makes the conclusion you quoted.

Look at the chart below taken from his article. The bottom blue-dashed line is the baseline barrel. It is as heavy as the heaviest fluted barrel. The top RED line in the dynamic graph is the baseline barrel after fluting. Notice that it also has the HIGHEST muzzle deflection.

The 1.222 muzzle dia. fluted barrel weighs the same as the .8 dia. baseline barrel. The brown line represents its' deflection and it is the stiffest on the graph. This is what should be as the diameter is the greatest. If the 1.222 barrel was left UNFLUTED, it would be much stiffer yet and would be the stiffest one on the graph.

As to whether any of the simulated barrels would be more or less accurate than one of the others, it is far more dependant on the quality of the rifling, bore and barrel steel than if it is fluted or not or is lighter or heavier. Just because one rifle has a heavier barrel does not guarantee that it will outshoot the lighter one. Too many variables to predict that outcome by weight alone, but it IS guaranteed that the heavier contour WILL be stiffer....for what it is worth.

Varmint Al tried his best, but worded some of his conclusions contrary to what his graphs depict. Look at the one below closely and you will see that what he said in your quote is NOT what the graph shows.
 

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Thanks recoilrob, I actually set down with two of my FEA specialists today and they explained the whole theory to me. As you previously stated, you want max OD, they even brought up a tubeing string they are analysing and showed me how changes in the od affected stiffness.

I feel much smarter now, but I did get a headache from all the math.
 
From what I have always been told you flute a barrel for weight considerations first then the increase in surface area helps cooling ( by how much is for the engineers to compute) and third for aestetic value. But it must be done prior to final machine work and heat treating.
 
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