Barrel contour and accuracy

[sudnit5]

I was wondering if different barrel contours affect accuracy. My McMillan is cut for a Rem varmint contour and I was wondering if getting a match barrel in that contour would be okay.

 

[RemingtonSPS]

Re: Barrel contour and accuracy

We have had good accuracy out of a #5 sporter. That is as light as we have gone and still had great repeatable accuracy. After 3-5 shots the barrel begins to get pretty hot. Match and Varmit rifles usually go with heavier steel for that reason. The Varmit contour is a good contour. It is also thought that heavier barrels have better harmonics and thus tend to be more accurate.
If i were building a long range hunter #5 is as light as i would go. If i were building a tactical rifle Varmit contour is as light as i would go.

 

[sudnit5]

Re: Barrel contour and accuracy

Thanks. Right now I have a Shilen Select Match #17 in 1:12 .30 caliber that I was thinking about putting on there. I have read so much about the different barrels, I guess I just need some confirmation that this one will be good. I am going to use it for tactical only, no hunting.

 

[mildot326]

Re: Barrel contour and accuracy

Where does the "sendero" contour fit in?

 

[RemingtonSPS]

Re: Barrel contour and accuracy

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: mildot326</div><div class="ubbcode-body">Where does the "sendero" contour fit in? </div></div>

Almost identical to the Varmit.

 

[RemingtonSPS]

Re: Barrel contour and accuracy

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: sudnit5</div><div class="ubbcode-body">Thanks. Right now I have a Shilen Select Match #17 in 1:12 .30 caliber that I was thinking about putting on there. I have read so much about the different barrels, I guess I just need some confirmation that this one will be good. I am going to use it for tactical only, no hunting. </div></div>

Its worked well for me.

 

[excess]

Re: Barrel contour and accuracy

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Someone mentioned harmonics earlier. I am not sure that is all the answer, but at the same time I am not sure it isn't. Harmonics are pretty easy. Attached is a picture of (roughly) what the first natural frequency of a 26" Bartlein MTU barrel looks like. That frequency is around 68 Hertz. Would be pretty easy to make comparisons with other contours, with or without fluting, etc.

 

[ggmanning]

Re: Barrel contour and accuracy

I have a Model 7 .243 (bedded, tuned trigger, tuned handload) with a wispy little 20" sporter barrel that my daughter uses to deer hunt. It is suprisingly accurate for a stock gun but as stated above it heats up very fast and starts to string groups. Not quite as good as my customs but it will print .80-.85 range consistently at 100 yds if I don't shoot it more than 5 times. Great for a hunting gun...but you'd spend all day waiting on it to cool if you tried to print much paper. I think initial accuracy is potentially as good with light contours vs heavy contours but not with any volume in a short time period.

 

[RemingtonSPS]

Re: Barrel contour and accuracy

My buddy did a .260 on a #5 sporter. It will do 5 shots in the .3's at 100yds. I have seen the #3 do really good 3 shot groups but not as consistently as the #5's. For hunting .8's would be good.

 

[sudnit5]

Re: Barrel contour and accuracy

Thanks for the input everyone. CNC, that's interesting about the harmonics. I never knew about that.

 

[Terry Cross]

Re: Barrel contour and accuracy

CNC,

What caliber bore was that graphic modeled for?

Wouldn't two barrels of the same contour but different bore size have different harmonics?

Would two barrels of the same contour but different theaded shank lengths have different harmonics?

Would two barrels of the same contour but different torque against the receiver have different harmonics?

Not making fun or picking on your post at all. I have wondered about these variables but do not have the technical expertise to test nor the engineering experience to know.

Thanks,
TC

 

[Outsydlooknin75]

Re: Barrel contour and accuracy

I wish that the barrel makers or someone who make a spread sheet of ALL the different contours and how they compared to each other.

How many times has the question, "Will X profile fit in a stock for an X profile but from a different maker". I think it would be great if there was a standardization between the barrel makers and their contours.

 

[Emouse]

Re: Barrel contour and accuracy

Look at the Lothar Walthar home page ( parent site/Germany) They have all the diffrent profiles and dimensions.

Hope this helps?

 

[JJones75]

Re: Barrel contour and accuracy

I've got a 20" Kreiger , light Palma conture in 308 that will shoot FGMM 168s into .3's for 5 shots string after string after string with only a couple min between groups.

i think barrel quality and proper fitting plays ALOT bigger role than barrel weight , maybe if your shooting 10 shot strings or somthing a big old fat barrle will be better , I just don't see the benifit of all that added weight anymore.

 

[excess]

Re: Barrel contour and accuracy

Terry,

Understand I saw this and decided to give just a what-if, somewhat of a demonstration of what can be done. In this case I chose a 30 caliber bore - the most popular still I think.

As for your second question, the bending stiffness of the barrel (or a beam for a more traditional engineering application) is defined much more by the outer diameter than the inner. That said, it would be an easy analysis to show exactly what difference it does or does not make.

To your third question, I would say absolutely. In this case I looked on Surgeon's website and picked the shank length for their 591 receiver. I'm sounding like a broken record here, but it would a very simple thing to show exactly what an effect shank length does or does not have.

And for your fourth question, I think so. That analysis gets slightly more complicated (in my mind that becomes what we call a non-linear analysis rather than a linear analysis). Still not terribly hard to do though.

I knew you weren't making fun of me. I've tried to get one of the action manufacturers attention on this before to no avail. As I see it right now some really smart people (GA Precision, KMW, Surgeon, Bartlein, Krieger, and so on (in no order)) have done an amazing job at what they do, but I still think there is more that can be done with some engineering analysis. Some of the things I think may have opportunity are analyses of action stiffness, barrel stiffness, composite stock stiffness, and maybe most importantly the whole thing as a system. Maybe you guys have already put together the best there can be, but maybe there is some more to be gained too? Also, we can do analyses for heat transfer to understand exactly how it affects things, and how quickly things heat up and cool back down, etc.

I am an engineering nerd whose biggest hobby is guns and shooting, so I enjoy trying to pair the two.

Thanks for your interest,
Chris

 

[Lburt]

Re: Barrel contour and accuracy

go to Kriegerbarrels.com, (Krieger only makes match barrels) and compare #6 heavy bull sporter, Remington Varmint and #7 Light Varmint contours. What adds the weight to #7 is that it is a straight taper. Krieger will also custom contour for you but the Remington varmint is a great contour for a hunting rifle. If you decide to flute and chop it off to around 22", you can cut about 12 oz.

 

[sudnit5]

Re: Barrel contour and accuracy

Thanks, I have looked at their site a lot lately. I do plan on cutting the barrel to 22".


<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: LarryB</div><div class="ubbcode-body">go to Kriegerbarrels.com, (Krieger only makes match barrels) and compare #6 heavy bull sporter, Remington Varmint and #7 Light Varmint contours. What adds the weight to #7 is that it is a straight taper. Krieger will also custom contour for you but the Remington varmint is a great contour for a hunting rifle. If you decide to flute and chop it off to around 22", you can cut about 12 oz. </div></div>

 

[jbell]

Re: Barrel contour and accuracy

I was under the understanding that a specific countour has nothing to do with "inhearent accuracy" of a barrel. It does however effect how the accuracy things like heat are applied and also a heavier barrel is easier to hold steady. What I mean to say is if you take a barrel (cut rifled) of a straight contour (no taper) and shoot it then contour it and shoot it agan the inhearent accuracy will not change untill you reach a point where the barrel is to thin for the given caliber (well thinner than a feather weight ect). Has anyone heard of what I am tring to describe?

 

[clmayfield]

Re: Barrel contour and accuracy

Varmint Al, a mechanical engineer by trade, did some work on barrel harmonics. You can find it here: http://varmintal.com/atune.htm.

He was specifically testing tuners, but what he ended up finding with his models was that shorter and thicker is better because the vibration is dampened. This is different from finding an appropriate node, the overall vibrations are dampened because of the stiffness, which is a good thing.

He also found that even an "out of tune" tuner should promote accuracy. Interesting stuff.

 

[WRM]

Re: Barrel contour and accuracy

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Carter Mayfield</div><div class="ubbcode-body">... but what he ended up finding with his models was that shorter and thicker is better because the vibration is dampened.... </div></div>

Shorter/thicker = more rigid = less movement = more accurate, theoretically....

See Dan Lilja's barrel rigidity calculations/comparisons.

Cheers,

Bill

 

[clmayfield]

Re: Barrel contour and accuracy

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: WRM</div><div class="ubbcode-body"><div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Carter Mayfield</div><div class="ubbcode-body">... but what he ended up finding with his models was that shorter and thicker is better because the vibration is dampened.... </div></div>

Shorter/thicker = more rigid = less movement = more accurate, theoretically....

See Dan Lilja's barrel rigidity calculations/comparisons.

Cheers,

Bill</div></div>

I've see that article before. Dan Lilja is a smart guy... very well versed in the theory. The stuff he puts out there is always an interesting read.

 

[FreshKills]

Re: Barrel contour and accuracy

Fret the interior of a barrel,not it's exterior,which is of course rather moot.