dmoran
Donovan Moran
To what accuracy level will 30-shots in 7-1/2 minutes hold, and from what contour barrels, are your claims?
What kind of rifle, caliber, and firing position are your claims from?
Last edited:
Barrel Contour vs Accuracy
- Thread starter Phil3
- Start date
What kind of rifle, caliber, and firing position are your claims from?
LA50SHOOTER
Sworn To Protect The Constitution.
- So, None of us on here knows anything about barrels or steel or for that matter reality about barrels. - We just like spending a lot of money on big worthless hunks of unnecessary steel ?
dmoran
Donovan Moran
@LA50SHOOTER
I totally believe @Bart B. to be correct, but not to the accuracy levels or disciplines most people here are referring to.
And as you and many of us know, definitely not to benchrest capability, where so many of us have seen first hand how barrel heat can and does open up grouping capability.
I totally believe @Bart B. to be correct, but not to the accuracy levels or disciplines most people here are referring to.
And as you and many of us know, definitely not to benchrest capability, where so many of us have seen first hand how barrel heat can and does open up grouping capability.
Alex Wheeler
Site $$ Sponsor
I have been quite interested in contours over the last couple years and how they can effect harmonics. My opinion from what I have seen is amplitude is effected most with contours. The smaller sporter contours have a much greater amplitude than the heavy contours, they can tune in just as well, but will be worse when out of tune. The difference between the heavier contours is small enough I doubt you will see much difference unless your at the top level. I will leave it as bigger is not always better unless you need the heat sink.
you can use a shortish piece of dowel rod and wrap it with pipe wrap tape (10 or 20 mil) until it, plus the sandpaper, are about the diameter you want. you can sand off to the side with it and control which way the channel opens up. controlling the diameter with the tape makes the different sections of channel easy to work on.
LA50SHOOTER
Sworn To Protect The Constitution.
In a 'perfect world' the long skinny barrel will shoot very accurately, - no argument - I think that someone missed the 'point' that the OP was inquiring about. - I myself have little experience with factory contour barrels and there's a reason for it.
Exactly. Adjust the load or tuner and excellent accuracy happens. Such is life when the accuracy bandwidth is narrow.
Maybe I'm misunderstanding...how does a barrel with more vibrational amplitude translate to a narrow accuracy bandwidth? I'm thinking that I must be missing something here. A less stiff barrel will have more amplitude and a lower frequency. Both of these things add too tune bandwidth, as you called it.
For a given harmonic frequency, the width over time at the top few percent of it's bore axis up swing is less. There's less room for a given velocity spread to adjust load and/or tuning weight to get all bullets at their best exit angle.
That's as good as I can explain.
Alex Wheeler
Site $$ Sponsor
If we have a given frequency and increase amplitude, the barrel is moving much faster and will appear to have a narrow node. If you lower the frequency as well, then you would appear to widen the node. The problem with sporter barrels is that in my experience the amplitude increases much more than the frequency slows. So you end up with what appears to be narrower nodes because theres a lot more movement between nodes. Out of tune a sporter can shoot some big vertical. Vertical thats hard to achieve with a heavy barrel even if you tried. I have some different light contours to test, but they aint #3s you can take it too far IMO.
Last edited:
I'm in total agreement with Mike here.....
When Harold Vaught passed he was working on systems to "make barrels heavier and yet whippier" like he was fixated with tinning/leading barrel surfacess and trying to affix lead sheathing in an attempt to INCREASE BANDWIDTH..... as he knew full well it's a trade-off.
BTW, I also firmly believe that "that's as good as I can explain" is code for "you wouldn't understand it" which is code for "if I told you I'd have to kill you" which is code for "I don't REALLY know what I'm saying, but I'm saying it ennyways" which is code for "That's My Story And I'm Sticking To It!"
Hang tuff Mike.....
When Harold Vaught passed he was working on systems to "make barrels heavier and yet whippier" like he was fixated with tinning/leading barrel surfacess and trying to affix lead sheathing in an attempt to INCREASE BANDWIDTH..... as he knew full well it's a trade-off.
BTW, I also firmly believe that "that's as good as I can explain" is code for "you wouldn't understand it" which is code for "if I told you I'd have to kill you" which is code for "I don't REALLY know what I'm saying, but I'm saying it ennyways" which is code for "That's My Story And I'm Sticking To It!"
Hang tuff Mike.....
I shouldn't have stepped in this. I think I'll sit this one out. I've already stated my position on this subject in other posts.
No need in me hashing things out again here. I'll let others do it this time, Al. Thanks for the support, though.--Mike
For folks wanting to learn about barrel vibrations' amplitude and frequency concepts across several profiles, use this link:
http://www.geoffrey-kolbe.com/articles/rimfire_accuracy/barrel_vibrations.htm
Use a fixed barrel length to see how muzzle angle changes for a given load's barrel time.
Kreiger Barrels site has profile dimensions for all sorts of barrels for comparison.
http://www.geoffrey-kolbe.com/articles/rimfire_accuracy/barrel_vibrations.htm
Use a fixed barrel length to see how muzzle angle changes for a given load's barrel time.
Kreiger Barrels site has profile dimensions for all sorts of barrels for comparison.
Last edited:
Bart B........
Let me fix that.
For folks wanting to learn about Geoff Kolbe's ideas and proposals with an included computer modeling facility re barrel vibrations' amplitude and frequency concepts across several profiles, use this link:
There are many sites on the net proposing computer simulacrums and simulations of all sorts of things from "global warming" to "sustainable power"....... the fact that they exist doesn't make them tenable.
GIGO is a broad appellation and "computer modeling" rarely depicts or predicts real world results.
Your ignorance just got revealed.
Look on the flip side of your GIGO coin. It stands for Good In, Good Out. Recent examples of good computer modeling stuff in ballistics put men on the moon, rovers on Mars and camera fly buys of other planets including Pluto. Not to mention designing earthquake resistant tall buildings that do not vibrate very much at all as Richter scale magnitudes rise. All those wonderful ballistics software programs we use are computer modeling things.
Computer modeling uses the same formulas used on slide rules and in long hand math that started over a century ago. They just speed up and shorten the time to results. The 2 basic and 2 first shortcuts making up the 4 main fundamentals have been around for thousands of years.
Don't let your reply to this make you look dumb nor stupid; I don't think you are either.
Last edited:
Ok, I'm gonna wade in here just a little bit.
You hit the nail on the head when you said that amplitude reduces with mass OVER TIME. The barrel is already deflecting downward before a shot is even fired, due to gravity, though. So, it's first movement is downward as the bullet begins it's travel down the bore. Because the barrel is pre loaded by gravity, it will come up and ultimately, the travel be larger..due to the energy held with the material. Replace travel with amplitude. INITIAL amplitude is increased, but you are right, over time it is less. We are not talking about natural frequencies of a cantilevered beam here, either and we certainly are not talking about much time.
But, at a given frequency, more muzzle deflection, initially, is equal to more initial amplitude. Forget what happens over time as we are dealing with not only natural frequencies but the forced deformation that happens while the barrel is under pressure and slightly after.
To the point...more muzzle deflection equals more amplitude and a larger arch or barrel oscillation. This is clear on target by the large out of tune groups vs. a stiffer barrel and this alone is evidence that the amplitude during the small amount of time involved is increased, not decreased. The larger radius or arch, for lack of a better word, is how mass widens the tune window. This is why a somewhat heavier tuner is best, IMHO. It both increases INITIAL amplitude and decreases frequency. In a nutshell. It slows the barrel down and makes it move in a larger "radius" at the node.
I found this interesting when doing the vibration analysis testing for my tuners because it is counter to common physics studies that mostly address amplitude "over time." But bottom line...initial muzzle deflection is increased by having a mass at the end of the barrel when fired. We measured the amount and times to the point that this was visible when testing different media in my tuner than the tungsten powder matrix that I use for dampening. Regardless of the point you are making, during the time that matters, amplitude is increased by having more muzzle deflection. The only caveat I'll add is that we were testing the affects of adding a mass to the end of the barrel. I don't see much difference though, as adding mass simply makes the barrel act less stiff.
I'm not gonna debate this because I physically measured it and one of my New Year's resolutions is to stay out of pissing matches on here. We'll have to see how that one goes..."over time."
I do like to read your posts and you are a smart man. This is very much a less than obvious result to expect if going strictly by what most research involving vibration will tell you. The key is time. There just isn't enough time before bullet exit occurs to see a net reduction in amplitude. I'm sure the numbers can vary a bit with different barrel stiffness's and the forced deformation that occurs both with and without weight added at the muzzle though. --Mike
Alex Wheeler
Site $$ Sponsor
I have been limitedly successful with some of my ideas. Not being willing to discuss my ideas when challenged is not how I learn. I have seen things that have made me change opinions and sometimes I look back on thoughts I now believe are wrong. Its OK to be wrong or change or develop your opinions.
THIS from the guy who, on my first post ever on this board answered "We don't like nor want your BRC type over here... please leave"
seriously Alex?
You "want to discuss" with people who'll agree with you and stroke your ego..... that's not "discussion" ...... that's a group of like-minded people gethered together for some barbeque and beer.....
Alex Wheeler
Site $$ Sponsor
If your going to use " " at least quote what I actually said. Heres the post your referring to http://forum.accurateshooter.com/th...recoil-reduction.3926863/page-4#post-36988050
And posting a quote that basically calls anyone who disagrees with Mike a fool sure doenst change my mind about your attitude.
Last edited:
Upgrades & Donations
This Forum's expenses are primarily paid by member contributions. You can upgrade your Forum membership in seconds. Gold and Silver members get unlimited FREE classifieds for one year. Gold members can upload custom avatars.
Click Upgrade Membership Button ABOVE to get Gold or Silver Status.
You can also donate any amount, large or small, with the button below. Include your Forum Name in the PayPal Notes field.
To DONATE by CHECK, or make a recurring donation, CLICK HERE to learn how.
Click Upgrade Membership Button ABOVE to get Gold or Silver Status.
You can also donate any amount, large or small, with the button below. Include your Forum Name in the PayPal Notes field.
To DONATE by CHECK, or make a recurring donation, CLICK HERE to learn how.