I see a lot of the F-class shooters are using a straight contour barrel. Many years ago Creighton Audete told me a straight taper barrel was stiffer than a no taper barrel. Please help me choose a new barrel. Any Engineers out here?
Barrel contour
- Thread starter 10XSHOOTER
- Start date
Ned Ludd
Silver $$ Contributor
A tapered barrel will never be stiffer than a straight contour barrel (i.e. no taper) of the same breech diameter (i.e. 1.25"): more metal means a stiffer barrel, and metal had to be removed to create the taper. The caveat to that is that the straight contour barrel with the same breech diameter will also weigh a lot more.
FWIW - not so many F-TR shooters are running straight contour barrels due to their weight (i.e. 18.18 lb weight limit in F-TR). Doing so would likely limit overall barrel length to 28" or less. Heavy Palma, Heavy Varmint, MTU, M24, and other heavy tapers are much more commonly found among F-TR shooters, typically at around 30" finish length. F-Open shooters enjoy a 22 lb weight limit that often allows them use straight contour barrels, 1.25" straight contour being the most common, and in lengths of up to 32" to 34".
FWIW - not so many F-TR shooters are running straight contour barrels due to their weight (i.e. 18.18 lb weight limit in F-TR). Doing so would likely limit overall barrel length to 28" or less. Heavy Palma, Heavy Varmint, MTU, M24, and other heavy tapers are much more commonly found among F-TR shooters, typically at around 30" finish length. F-Open shooters enjoy a 22 lb weight limit that often allows them use straight contour barrels, 1.25" straight contour being the most common, and in lengths of up to 32" to 34".
He was right! Now, per inch, a straight is stiffer than tapered, but not overall and stiffness is gained or lost much faster with length than with diameter. I post this from time to time but it's a link to a bbl stiffness calculator. Play with it and it might surprise you a bit. It's part of his weight calculator program...another good tool.
Computer Software - Lilja
We have five files available as a free download as indicated below. These are zipped files. Bullet Design Calculation Program – Available in two formats: Free Download as an Excel file or Free Download as an .exe file- more information on this software.Benchrest Barrel Weight Calculation Program...
FWIW, I find bbls that are extremely stiff to be a little harder to tune. They just show tune less clearly. I've gone to a little less stiff contours on my br rifles for this reason.
Sandstorm
Gold $$ Contributor
Pro's and Con's to everything and also caliber specific im thinking ...some just tune easier than others also.
I cant ever remember a 284 in a 9 twist not to tune in one 20 shot test..YMMV.
1.25 straight barrel of course.
Fair enough but a couple of things. I should've mentioned that I was referring to actual bbl deflection and how that shows on target while tuning, with a tuner. The other thing though relates to your 1.250 straight contour. I like them btw, but they are not necessarily stiffer than a little smaller contour. Length is more critical to stiffness than od. Go back a couple of posts and see the link I posted. It has a bbl stiffness calculator built into the program. At the very least, it surprises a lot of people to find that a couple of inches can make a hv stiffer than a 1.250. Play with that program a little bit. It's pretty interesting. IOW, I'm agreeing with you but it might not seem that way until you put some numbers into that program for yourself.
A slight thread drift but it is a complimentary thought.
A straight contour also has more mass, and that means it will be slower to heat up. Heat affects the barrel in ways that stiffness alone doesn't address, like wear, chamber/bore dia, etc.
A straight contour also has more mass, and that means it will be slower to heat up. Heat affects the barrel in ways that stiffness alone doesn't address, like wear, chamber/bore dia, etc.
Very true
Thank you All for your reply's I'll look at Mike's calculator.
Ranger188
Silver $$ Contributor
Article,
riflebarrels.com
A Look at the Rigidity of Benchrest Barrels - Lilja
While there are a number of factors that determine the accuracy of a rifle barrel, one of the more critical elements is its stiffness or rigidity. Obviously the larger in diameter a barrel is, the stiffer it will be. Almost as obviously, as the length of a barrel increases it becomes more...
Article,
A Look at the Rigidity of Benchrest Barrels - Lilja
While there are a number of factors that determine the accuracy of a rifle barrel, one of the more critical elements is its stiffness or rigidity. Obviously the larger in diameter a barrel is, the stiffer it will be. Almost as obviously, as the length of a barrel increases it becomes more...
I built a 2” x 35” .408 Cheytac on a 2 inch diameter Bat, similar to the Lilja example.
I would not even consider free floating such a barrel. It weighs 35 pounds itself. While a thicker barrel is stiffer if you secured the middle and attempted to deflect its ends, it’s not more resistant to droop.
We defeat the thickness of barrels somewhat by finding the part that holds all the weight, and thinning it dramatically from both the inside and the outside.
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Good article but his stiffness calculator is part of his bbl weight calculator program. Download it here..Article,
A Look at the Rigidity of Benchrest Barrels - Lilja
While there are a number of factors that determine the accuracy of a rifle barrel, one of the more critical elements is its stiffness or rigidity. Obviously the larger in diameter a barrel is, the stiffer it will be. Almost as obviously, as the length of a barrel increases it becomes more...
Computer Software - Lilja
We have five files available as a free download as indicated below. These are zipped files. Bullet Design Calculation Program – Available in two formats: Free Download as an Excel file or Free Download as an .exe file- more information on this software.Benchrest Barrel Weight Calculation Program...
You can put all those dimensions into the program and it'll tell ya. You have to play with it because the outputs are basically just a comparative number. So you have to put your numbers in and then compare it to another set of dimensions. You'll figure it out pretty quick, though. Most br contours are either 1.200 or 1.250 shank od, for some distance, then taper to whatever, at a given length. Generally, at the same length the fatter bbl will be stiffer but there's a point of diminishing returns to that statement due to muzzle weight being more on a straight than on a tapered bbl. Just play with the program. I put a lot of emphasis on the way a gun handles and a nose heavy gun is not desirable. Balance means a lot. You can play with the weight calculator too and see what different contours weigh, at different lengths and how stiffness is affected.
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