28 August 2001, 19:28
DB Bill
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Andr�
[This message has been edited by DuaneinND (edited 08-30-2001).]
The key to fluting is in the manufacturing of the barrel. To maintain proper accuracy and integrity the barrel should be drilled first then fluted. After the fluting the reaming and rifling can be finished. In this way the bore diameter can be left with the extreme accuracy of the reamer and the rifling which assumes cutrifling rather than button rifling. If done in the "normal" order of button rifling, fluting follows the finishing of the interior of the bore and groove. The metal of the barrel both relieves itself and gets compressed by the action of cutting the flutes. In essence, there are tight and loose spots in the length of the barrel which degrades accuracy and makes cleaning very difficult. In high volume fire the effects are worse. The effects are generally minimized by lapping which "evens out" the high and low spots by removing metal.
Another thing to consider in high volume fire is the shape of the rifling itself. Shilen makes barrels with a "ratchet" shape and Lothar-Walther makes barrels with a polygonal shape rifling, both of which are supposed to stand up to high volume fire. A drawback to these shapes is that they are accomplished with buttons and are not available in cutrifling.
Most of today's barrels are superb. The only overriding suggestion that I would make is to choose Stainless Steel no matter what brand or style as it will stand up to high volume better than chrome moly.
Bill
Thank you for the explanation! You obviously know from where you speak. I'm new to this forum but am already impressed with the depth of the gene pool.
Thanks to all for responding and I appreciate your advice. -MN
The affect of fluting on a barrel is in relationship to the location of the flutes to the material make-up of the barrel. If identical barrels, made in consecutive order were fluted, but the location of the flutes were placed in orientation to the rolled grain structure of the raw bar, there will be an effect on the accuracy of that barrel.
If a barrel is made properly for its fabrication method, there is no net accuracy differential based on the manufacturing method. Each of the three major methods have problems that result from the machining methods. It is the quality of the equipment and the skill of the workers that make the difference. Assuming the proper high quality material used for all three.
A properly made button-rifled barrel will not expand upon turning or fluting. This level of quality can not be determined by air gauges. They are too coarse for this measurement. Also, how a barrel is turned is critical too. The final lapping whether it is in a cut rifled barrel or a buttoned one will remove the problems caused by the individual methods of manufacture. If barrels made by either buttoning or cut rifling, are both made to the highest quality specifications, they will have equal accuracy capabilities.
In barrels which are stress free and properly made, the fluting is affected only by the following.
1. Placement in rotation of the grain structure of the barrel.
2. Placement in relationship to the rifling.
3. The combining effect from the numbers of lands and grooves and flutes. (vibration patterns)
4. Method used to flute and the fixturing of the barrel. Including:
A. Type of machine
B. Method of fixturing and damping.
C. Type of cutter
D. Program style.
E. Inter-relation of tool wear control and hydraulic pressure.
This last one is where a stress free barrel can be stressed by fluting and is the largest mode of failure for a fluted barrel and for reducing the accuracy in a fluted barrel.
Thank you! That's what makes this forum great, all the input from people who know. I know the points that you make but I sometimes just get too lazy to write them all down fairly. I appreciate your time and efforts!
Bill
quote:
Originally posted by Bill Tompkins:
Woody,Thank you! That's what makes this forum great, all the input from people who know. I know the points that you make but I sometimes just get too lazy to write them all down fairly. I appreciate your time and efforts!
Bill,Thanks. Seeing a craftsman making cut rifling is to me identical to the battle between the pitcher and batter in baseball. It is a personal endeavor. Here, monitoring the computers and electronics sometimes is too sterile. The craftsmanship is in watching for the slightest change in the barrel. Then repeating the process a thousand times.
Bill
The animals don't just stand and let you shoot them I don't think...You will have to move your position quite often and the barrel will cool sufficiently during that time...I consider flutes a waste of money..A heavy barrel heats up slower by the way...
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Ray Atkinson
This is a lot of shooting in a short period of time. Particularly an additional 20+ shots on a barrel that will burn skin. If 40 fast shots is indicative of the type of shooting done in this culling operation, you are in the realm of what full auto guns get into. NO amount fluting, nor even spraying the barrel with cold water will help in the long run. To most barrels, this type of shooting will cause long term rapid wear to a barrel. Here is a suggestion that may help. First, it may be possible to create a perforated shroud around the barrel where the forend is. This will protect the skin from the random bump. For the barrel, there are two separate solutions. So, secondly, the replacement of the barrel with one which is suitable for volume of fire is a better answer. Solution 1 is to obtain a chrome plated military barrel and if possible fit it to the action. This would be the lowest cost solution. Solution 2 is to contact us (Lothar Walther) directly and get a barrel that is designed for this type of firing. LW 50 Stainless, polygon bore. Then have the LO-WAT process done. This will give you excellent barrel life and accuracy, but it more expensive than solution 1.
Since you are having this much fun, being able to operate with a hot barrel is a better solution than spending money which will not guarantee a result. But, for normal culling, Ray is right.
Woody
Please let me add a few words to the excellent discourse that Mr. Tompkins has already offered.
My experience with fluting is the all of the factory, and most of the custom, fluting work is cosmetic. First they do not cut enough flutes, and they do not cut them in an advantageous shape.
I have three rifles that have either 12 or 16 flutes on their barrels. These flutes are cut in the shape of a piece of pie. They are spaced so that the almost come to a sharp point at the top.
Using the example of my 16 flute, 1 inch diameter 28 inch long barrel I calculate the following:
- Non-fluted barrel's surface area - 84.82 square inches
- Fluted barrel's surface area - 214.49 square inches
That's a surface area increase of 152.87%. Anyone who thinks that is insignificant doesn't understand Physics.
I would highly recommend that you consider this type and number of flutes. Also, please consider having your barrel Cryogenically processed after the fluting to remove any residual stresses imparted by the machining.
Good Hunting !
[This message has been edited by Pumba (edited 09-02-2001).]
A better option is to have 2 and better yet 3 rifles, thats is how I have handled that in the past, unless one feels justified in ruining a barrel and marking it down as a trip cost and thats very feasible..Just rebarrel it when you get home or when the accuracy goes for $300. I have done that on one ocassion...
The wood was charred and the stock had to be re-inletted for a very slightly larger barrel to cover that up...
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Ray Atkinson
I have to say that I am amazed at this discussion, and I generally expect a lot from our members.
I seldom make absolute statements, (they cause arguments!) but I will say authoritatively that on NO other website in the world are you likely to get two top-notch barrel makers trading insights like see here. Throw in shooters from Australia to Africa to Idaho and you really have the makings of a good discussion!
I'm not familiar with Woody's LO-WAT process, what's that? I will say what everyone's considered too obvious so far, and point out that it's the lands in the throat that go out first in this type of shooting.
Although it is unlikely to yield the absolute ultimate accuracy, sub-MOA chrome-lined polygonal-rifled machine gun barrels are available that will stand up to the punishment for tens of thousands of military rounds.
I seem to remember that FN has recently made a new sniper/tactical rifle using this method. I will check my magazine stack to see if I can find the article. With all deference to Woody, this seems the right answer for the problem at hand.
I have a buddy with a chrome-lined .308 barrel on a German MG42(??) that shoots it until at night you can see the bullet as a dark spot in the glowing barrel on a slo-mo video. He had a case neck separate and shoot down the barrel, resulting in a stuck case on the next fired round. After case removal all was OK!
Don
The barrels in my first solution were the take off or new machine gun barrels. As these were the less costly way to go. If a person can get one long enough and heavy enough to do the job. The gas hole may be the only real problem. This too could be eliminated by putting a band over it. The other solutions would cost more and therefore may be of less interest.
Lo-Wat is a process whereby the surface of the inside of a barrel is nitrided so as to give a longer life with hotter rounds but without going to a chrome plating and reducing accuracy.
Most people assume that a barrel maker does something a particular way. They cut or button for example. Or they work in a particular area of the market. Lothar Walther is the absolute opposite. We are the only civialian barrelmaker with two plants. We dedicate what others would use for advertising into our R&D program. We are a large producer yet a single barrel for a hunter or benchrest shooter is equally important. Because of the erosive nature of many of the newer cartridges, we developed LW 50 stainless. Solving customers stranger problems is viewed as being fun. When a shooter has a question, then a knowledgeable person is who they get, not a marketing person. We even designed some of our processes so as to help the individual gunsmith be more profitable.
I do not make these statements in open forum to attempt to sell a barrel, but instead to be proactive within the world shooting community. We work with the entire shooting market in the free world. OEM, High Grade OEM, SAAMI, CIP, Custom Shop, Prototype, Benchrest and Airgun.
I am personally working on special orders today, Saturday, 1 Sept. even though it is a national holiday in the US. The customers come first. In fact, Ray's 375 barrel is having its program written tomorrow.
Shooters and hunters are derided all over the world. Hunting is under attack in most places. I want to put the best foot forward and work to help this sport and the people in it. And Don, this site is the most comprehensive of any gun related site.
As to my particular application, Ray hit on it...I'll gladly come back after the trip and have a new barrel installed. I'm paying to have this kind of shooting action and if the barrel gets worn out then I indeed got my money's worth!
I'm getting off the subject a bit, but let me explain I changed my direction several years ago. Found myself in possession of a bunch of good rifles that weren't getting enough of their intended use. Instead of hunting and shooting, I was slipping into looking and talking. So I sold off the "collectors" and started getting my money's worth out of the ones I kept. While I have no junk, I don't mind scratches and bluing wear as long as it was come by honestly. With luck, I'll keep some of these talented barrel makers up above here in work! "Shoot 'em if you got 'em"! -MN