Contouring barrel tech

[Scott-ak]

I am a pretty competent machinist. I can make square things round and round things square and hit the dimensions required
I have chambered a couple barrels and turned some blanks into ARs. I practice using low cost blanks like those from Green Mountain.
I have not studied the 'science', if there is any, associated with barrel contours. I have looked at some manufacturers 'specs'.
I have a 9mm blank that I want to use to turn into a 16" shooter to go with some fast moving 95gr loads I've been toying with. There is no practical reason other than I can, so I will. I've done some in short lengths and simply made up a profile and turned them. This time I'd like to put a little more ?science? into it. Eventually I'll turn something with more class.
Are there any books or literature about the reasoning for different profiles? Something deeper than "light weight" for packing or action shooting and heavy for targets. Maybe stuff with suggested contours for different results??? Say for instance I was to flute a barrel. Is it preferred to have a larger major diameter? how much larger? Is a pencil profile better than a constant taper? etc etc
If you've got some of this knowledge in your head and are willing to share it, it would be appreciated.

 

[Will Henry]

There are those who have said the original Mauser contours were designed to compliment the cartridges for which they were chambered. Maybe, maybe not. There is little doubt that barrels with more taper will vibrate differently than one of the same weight but with less taper. Barrels with a swamped contour will also vibrate at a different frequency and amplitude than a quick taper. Just what this translates to, as far as accuracy is concern, is still debatable or people would not still be trying different stuff. WH

 

[tobnpr]

Say for instance I was to flute a barrel. Is it preferred to have a larger major diameter? how much larger? Is a pencil profile better than a constant taper? etc etc

Everything, and then some, on effects of barrel fluting:

Varmint Al's Fluted Barrel Stiffness Analysis

My general rules of thumb...
Where weight is not a factor= length as required to obtain velocity needed for application.
As heavy a contour as can be accommodated by stock/chassis and shooter. Mass= greater ability to absorb heat from target shooting applications.

Where weight, barrel length are a factor- as in most hunting rifles- light contour taking into consideration any muzzle devices. Length based on needed velocity to obtain energy at impact required (game, max distance expected).

"Compromise" rifles (my term for rifles used for both) have contour based on weighing the trade-offs of weight and length. In any hunting application length is important to make sure MV can deliver needed energy.

"Accuracy" is unrelated to barrel contour. Light contour barrels can be just as accurate for a few shots as a varmint or bull contour- but will string shots due to overheating if used in a target application.

 

[Scott-ak]

great stuff, thanx!

any more out there?