The Firing Line Forums

Go Back   The Firing Line Forums > The Hide > The Art of the Rifle: Bolt, Lever, and Pump Action

Reply
 
Thread Tools
Old March 4, 2013, 02:38 PM   #26
Sweet Shooter
Senior Member
 
Join Date: June 17, 2011
Posts: 515
@Bart B.
I don't buy it. Why then would gantry cranes not have round booms instead of triangles? Except for Remington's triangle shape barrels (which subtract surface area—excluding material) surface area is increased by fluting. I'm not saying it that in doing so includes more material, but if you measure stiffness as deviation x weight a fluted barrel will be stiffer. Someone needs to do a test. by hanging a weight and measuring deviation with a micrometer on barrels. But that's probably a different thread.
-SS-
Sweet Shooter is offline  
Old March 4, 2013, 05:33 PM   #27
Picher
Senior Member
 
Join Date: December 14, 2004
Location: Maine
Posts: 2,889
Bart: I mentioned it for synthetic stocks primarily because wood stocks, and to some degree, laminated stocks can change POI through seasonal and age warpage/shrinkage, so should be free-floated without any question in my mind.

Synthetic stocks are not generally subject to the seasonal and age changes, so if someone really wants a pressure-point on those rifles due to use of various loads, it makes more sense, provided it's tested and works (for them) in various conditions.

JP
Picher is offline  
Old March 4, 2013, 05:58 PM   #28
Bart B.
Senior Member
 
Join Date: February 15, 2009
Posts: 5,412
Sweet Shooter, your forgot the following in the link I posted:

Quote:
Deflection at the Muzzle
If you are still not convinced that fluting DOES NOT increase stiffness, I offer the following theoretical explanation.

Let us take all three barrels and place them horizontally in such a way that we permanently affix one end to a fixed position and the other end will basically be free-floating. In other words, let us say that we are welding the threaded end of the barrel to the side of an M1A1 Main Battle Tank. Let us say that the weld is so strong that it is impossible to break the connection. Now, let us say that we will exert a vertical force of 500 pounds at the muzzle of the barrel. So basically, the threaded end is fixed to a tank while a 500-pound man is standing at the muzzle of the barrel. Do you want to know how much the muzzle end will deflect?

The 10FP (non-fluted) will deflect 4.4 inches. The 12BVSS (fluted) will deflect 7.5 inches and the Light Varmint will deflect 9.5 inches. Enough said.
Such stuff is easy to calculate; mechanical engineers doing vibration analysis of stuff to survive earthquakes do that all the time. It's grade school physics to them.

Here's more info on fluted barrels:

http://www.varmintal.com/aflut.htm

Best thing for you to do is find a mechanical engineer then have him explain it. Decades ago, when I thought like you about it, I asked a mechanical engineer about it. He asked me about a wood sun deck's construction. "Which would be stiffer , 2x8's glued together vertically or alternating 2x6's and 2x8's glued together vertically?" The 2x6's are exactly like 2x8's that had an inch cut off their 8 inch dimension. Go figure.

Why would gantry cranes not have round booms instead of triangles? I don't know for sure but it's probably something to do with the single-plane (vertical) force/load axis they're used for coupled with cost, material weight and usability. Contact a company that makes 'em then ask why triangle instead of round shaped booms; remember their answer. Then you'll know more about them than I do.
__________________
US Navy Distinguished Marksman Badge 153
Former US Navy & Palma Rifle Team Member
NRA High Power Master & Long Range High Master
NRA Smallbore Prone Master

Last edited by Bart B.; March 5, 2013 at 11:44 AM.
Bart B. is offline  
Old March 4, 2013, 07:43 PM   #29
reynolds357
Senior Member
 
Join Date: December 10, 2012
Posts: 2,514
Tell me if I am wrong Bart but the way I have always understood it is that weight for weight a fluted barrel is stiffer than a non fluted. Meaning we would be comparing something like a fluted bull to a non fluted varmint.
reynolds357 is online now  
Old March 4, 2013, 08:50 PM   #30
Bart B.
Senior Member
 
Join Date: February 15, 2009
Posts: 5,412
Reynolds, you're right. For equal weight, the fluted one's stiffer. That's 'cause there's more metal further away from its center of mass resisting it being bent.

Regarding those Winchester barrels, both types have the same outside dimensions for a given caliber. Fluting one makes it lighter as well as less stiff than the solid one.
__________________
US Navy Distinguished Marksman Badge 153
Former US Navy & Palma Rifle Team Member
NRA High Power Master & Long Range High Master
NRA Smallbore Prone Master

Last edited by Bart B.; March 4, 2013 at 09:28 PM.
Bart B. is offline  
Old March 5, 2013, 08:20 AM   #31
Picher
Senior Member
 
Join Date: December 14, 2004
Location: Maine
Posts: 2,889
A fluted barrel is somewhat heavier and stiffer than a barrel the diameter of the bottom of the flutes. It may or may not be as accurate as before fluting.

Often, fluting makes barrels less accurate, however if the barrel is button-rifled after fluting, accuracy is often better than barrels fluted after rifling.
Picher is offline  
Old March 5, 2013, 09:58 AM   #32
Bart B.
Senior Member
 
Join Date: February 15, 2009
Posts: 5,412
Picher, you're right; rifling of any type is best done after the gun-drilled blank is fluted.

Folks who've air gauged barrels for very accurate groove diameters have seen the following for different rifling processes watching the bubble move up and down on the pressure gauge as the gauging head's moved back and forth in the bore:

* Button-rifled ones; grooves are swaged out from bore diameter (4 to 5 thousandths inch in one pass) creating outward stresses. Fluting button-rifled barrels makes the groove (and bore) diameters larger under the flutes and there's a bump at each end of the flutes.

* Hammer-forged ones; lands are swaged inward from multiple hammers pounding the barrel blank onto the spiral-fluted mandrel it's on creating inward stresses. Fluting hammer-forged barrels makes the groove (and bore) diameters smaller under the flutes and there's a bump at each end of the flutes.

* Cut-rifled ones; grooves cut (scraped) out from bore diameter (a few ten-thousandths inch for each of many passes of the cutter in each groove) creating virtual zero stresses. Fluting cut-rifled barrels typcally does not change the groove (and bore) diameters larger and there's no bump at each end of the flutes.

Same thing happens when you turn down a finished barrel of each type to make it lighter. I've known more than a few owners of best quality Hart button rifled match barrels turning off a tenth of an inch to make them lighter; they lost the gilt-edge great accuracy they had in their original diameter.
__________________
US Navy Distinguished Marksman Badge 153
Former US Navy & Palma Rifle Team Member
NRA High Power Master & Long Range High Master
NRA Smallbore Prone Master

Last edited by Bart B.; March 5, 2013 at 10:09 AM.
Bart B. is offline  
Old December 14, 2013, 06:19 AM   #33
rpdtrvse
Junior Member
 
Join Date: December 13, 2013
Posts: 3
vanguard barrel

I have been reading both sides of the discussion on floating a vanguard barrel. I have a 30-06 vanguard I bought from a previous owner who rarely fired the gun. I took it out to the range simply because I upgraded the scope and went to sight it in. I found the groups were 2 to 3 at best. One suggestion was if the barrel is free floated. We checked with a dollar bill and found the barrel touching on the left side in front on the forend and about 8 inches back on the right side.
I got home a took the action out and found the marks the barrel had made in those areas but not on the pressure pad. I sanded them down until the barrel had enough clearance for a dollar bill to pass through folded. (about .012 of an inch). I went back yesterday and shot it again and it shot one three shot group inside a one inch square. another about 1 1/2 and a third about the same. It seems like the gun liked to be free floated and performed that way. This was letting the barrel cool down at least 5 minutes between groups. I agree with Bart B. on this topic.
rpdtrvse is offline  
Old December 14, 2013, 08:34 AM   #34
Picher
Senior Member
 
Join Date: December 14, 2004
Location: Maine
Posts: 2,889
I'm a free-floater guy, but the thickness of a dollar bill isn't adequate to keep the barrel from touching, especially near the forend tip. Barrels normally vibrate more in the vertical, but some do it with a little left or right. Resting the rifle against hard surfaces, or using a sling, can cause the barrel to touch the channel on firing if there isn't adequate clearance.

Try pinching the barrel toward the stock at the forend tip, to see if either the stock or barrel move to touching with about 3 lbs of side force. If it touches, you may want to open the channel more. Barrels touching on the sides under vibration usually causes diagonal groups, strung away from the side that touches.
Picher is offline  
Old December 14, 2013, 01:17 PM   #35
Josh Smith
Senior Member
 
Join Date: November 5, 2000
Location: Wabash IN
Posts: 524
Hello,

The purpose of floating a barrel is to eliminate the possibility of unknown pressure points.

If a company can make a stock so perfect as to eliminate pressure points and have perfectly even contact down the barrel, then the stock should add rigidity to the barrel.

Additionally, fluting may or may not add rigidity. The "blood groove" in the spine of a knife adds rigidity without making the knife heavier, so I'm inclined to believe the engineering principle is sound.

If nothing else, it increases the surface area and lets the barrel cool faster.

As for barrel floating: Has nobody heard of the new benchrest rifles? A lot of them are using bedded barrels with floating actions.

Regards,

Josh
__________________
Shootin' High?

Sights for the Mosin-Nagant
Josh Smith is offline  
Old December 14, 2013, 05:10 PM   #36
Bart B.
Senior Member
 
Join Date: February 15, 2009
Posts: 5,412
Josh, fluting a barrel makes it less stiff. Metal's been removed that made it as stiff as before fluting. It's like replacing every other 2x6 in a patio deck with a 2x4. Check out the following:

http://www.snipercountry.com/article...relfluting.asp

However, barrels of equal length and weight, one fluted and the other one plain, the fluted one's stiffer. It's got more metal further away from its center to resist bending.

Regarding those benchrest rifles with floating actions and the barrel gripped by something, that's been the standard for rail guns for decades. Sierra Bullets has used them since the '50's to test their bullets for accuracy because they want to eliminate all variables in the action and stock. They ride on a 3-point suspension rail. Some shoulder fired match rifles back in the early '70's have had their barrels clamped or epoxied in an 8" long aluminum block epoxy bedded in the stock's fore end. The action free floated in the stock with about 1/10th inch clearance all around it. Didn't shoot any more accurate than conventional epoxy bedding of just the receiver.
__________________
US Navy Distinguished Marksman Badge 153
Former US Navy & Palma Rifle Team Member
NRA High Power Master & Long Range High Master
NRA Smallbore Prone Master

Last edited by Bart B.; December 14, 2013 at 05:16 PM.
Bart B. is offline  
Old December 15, 2013, 08:58 AM   #37
Picher
Senior Member
 
Join Date: December 14, 2004
Location: Maine
Posts: 2,889
The weak sister in the theory of bedded barrels and floating receivers is the stock. Benchrest stocks are 3" wide and extremely stiff. Barrels are non-tapered. That's why it works well, but as Bart said, not necessarily better than bedding a very stiff action and floating the barrel.

Comparing benchrest bedding to sporter rifles and tapered barrels is foolish. The stocks aren't that stiff and tightly bedded, tapered barrels can overheat and cause problems.

Barrels sometimes will shoot tighter groups with a well-fitted pressure point, but the POI may vary with various rests, especially field rests and sling pressure, not to mention temperature and humidity variations.
Picher is offline  
Old December 15, 2013, 09:25 AM   #38
CTS
Senior Member
 
Join Date: November 6, 2011
Location: NE Georgia
Posts: 1,070
Quote:
However, barrels of equal length and weight, one fluted and the other one plain, the fluted one's stiffer. It's got more metal further away from its center to resist bending.
Right. to put it another way: the only way you can have a fluted barrel that is stiffer is if you start off with a much heavier barrel before fluting.
The cooling factor is the only good reason for fluting a barrel IMO, that is why most machine guns use fluted barrels. You can use a fluted barrel to lighten a hunting rifle but again you will likely give up accuracy due to the barrel being less rigid than the non fluted.
__________________
01 FFL, NRA, NAGR, GOA.
CTS is offline  
Old December 15, 2013, 09:44 AM   #39
Bart B.
Senior Member
 
Join Date: February 15, 2009
Posts: 5,412
Picher, competitive shooters in all disciplines have been shooting tapered barrels for decades. None of them change point of impact as they heat up. Even with 30 to 40 shot strings when fired every 30 seconds or less, they all hold point of impact to the Nth degree.

It's not the barrel's profile that makes them bend and change point of impact. They're either poorly stress relieved or fit to receivers whose face ain't square with the chamber/bore axis and the high point there puts more pressure on the barrel at that point as the metal heats up. And sometimes the shooter changes his hold on the rifle or its position on the body a bit later in the shot string and that is guaranteed to change point of impact relative to point of aim.

It doesn't matter how stiff a barrel or stock is. As long as they're repeatable in the way they whip and wiggle for every shot fired, best accuracy is at hand.
__________________
US Navy Distinguished Marksman Badge 153
Former US Navy & Palma Rifle Team Member
NRA High Power Master & Long Range High Master
NRA Smallbore Prone Master

Last edited by Bart B.; December 15, 2013 at 10:18 AM.
Bart B. is offline  
Old December 15, 2013, 10:33 AM   #40
Jimro
Senior Member
 
Join Date: October 18, 2006
Posts: 5,761
Quote:
Right. to put it another way: the only way you can have a fluted barrel that is stiffer is if you start off with a much heavier barrel before fluting.
The cooling factor is the only good reason for fluting a barrel IMO, that is why most machine guns use fluted barrels. You can use a fluted barrel to lighten a hunting rifle but again you will likely give up accuracy due to the barrel being less rigid than the non fluted.
I've never shot a machine gun with a fluted barrel. M249, M60, M240B, M2, or Mk19. Never saw a machine gun with a fluted barrel used by allies either, G43, DSHK, PKM, or RPK.

Barrel swaps are how machine guns deal with heat, except for aviation and coaxial machine guns which aren't in a position to swap barrels. Those guns just get hot.

Jimro
__________________
"Gorsh" said Goofy as secondary explosions racked the beaten zone, "Did I do that?"

http://randomthoughtsandguns.blogspot.com/
Jimro is offline  
Old December 15, 2013, 01:11 PM   #41
Josh Smith
Senior Member
 
Join Date: November 5, 2000
Location: Wabash IN
Posts: 524
Hello,

I'm not trying a direct comparison. I'm sorry if that's how I came off.

I love to play with theory. My dad is an engineer, and so I was raised by an engineer. My mom is an SLP who earned her teacher's license and has worked as a speech teacher in public schools for most of my life, so I was raised by a teacher.

The combination engineer/teacher team who raised me imparted a thirst for knowledge, a desire to question everything, and to form theories and find the similarities in seemingly different items.

Earlier I was speaking theory, what should work in a world of perfect circles.

In reality, my rifles have floated barrels, or, in the case of a Gew88, a sleeved barrel in which the sleeve does make contact at the muzzle.

The Mosin has a pressure point near the end of the barrel, with about 5lbs of upward pressure. The rest of its 29" length is floated. It should be noted that the Mosin barrel is tapered, albeit slightly.

Though I don't have one, the Lee-Enfield did use a spring-loaded pressure point in at least some models to improve precision.

The Gew88 is nice as is, so I left it alone. 1.2" at 100 or 110 yards with handloads makes me happy with a 120 year old rifle.

The Mosin needed help, so I did a bit more inletting to the beech stock and shimmed the action, gave the barrel a pressure point, and improved the trigger to a two-stage.

The Savage MkII BTVS was in sad shape from the factory. The action and barrel were not straight in the stock and the barrel was touching; after I got done with it, the heavy barrel floats and is very sub-MOA with correct ammo.

I love theory, but that's in a world of perfect circles.

In reality, I use what works.

If the Weatherby was designed for use with a non-floated barrel, heck, I'd leave it be if the barrel is bedded well in the stock.

If precision suffers after a few shots, I'd float it. This goes doubly for hunting rifles in which repeatability could be the difference between a hit or miss and there's no cool-down period.

Just some random thoughts on the subject, I guess.

Regards,

Josh
__________________
Shootin' High?

Sights for the Mosin-Nagant
Josh Smith is offline  
Old December 15, 2013, 05:01 PM   #42
Bart B.
Senior Member
 
Join Date: February 15, 2009
Posts: 5,412
Josh, the Brit's SMLE had a pretty whippy barrel due to its bolt's locking lug arrangement as well as receiver design. But it shot Cordite charged .303 ammo with a big muzzle velocity spread very accurate at long range. It was "the" rifle to beat in long range competition for decades. But Mauser 98 barreled actions in conventional stocks shot that same ammo more accurate at medium ranges, so their competitors had one of each type. Here's an engineering report of that rifle's ability to compensate for muzzle velocity spread at long range:

https://archive.org/details/philtrans05900167

In the "Read The Book" window, click on the "PDF" link to get the document.

I shot rifle matches with the stockmaker who designed Weatherby's early commercial stocks back in the 1950's. He also stocked and bedded a large number of match winning, record setting shoulder fired rifles in his day. He tried to convince Roy Weatherby to free float his sporter weight barrels, even proved to him that normal handling of the rifle's fore end could change bullet impact. But Mr. Weatherby would have none of that; he wanted a "perfect" fit of the fore end's barrel channel to the slender barrel and that was the rule.

Winchester free-floated some of their sporter barrels in sporter stocks some years ago, but sales of them were poor 'cause customers didin't like that 1/16th inch gap between the barrel and wood in the barrel channel. They quit that great idea.
__________________
US Navy Distinguished Marksman Badge 153
Former US Navy & Palma Rifle Team Member
NRA High Power Master & Long Range High Master
NRA Smallbore Prone Master

Last edited by Bart B.; December 15, 2013 at 05:35 PM.
Bart B. is offline  
Old December 15, 2013, 09:55 PM   #43
reynolds357
Senior Member
 
Join Date: December 10, 2012
Posts: 2,514
I honestly do not know how many MarkV Weatherbys I have. I think 8, but I would have to check. I have 2 v1's and 1 V2. None of them are floated. They are the only non-safe queen bolt rifles I own that I have not floated. ALL of them shoot way too good to mess with. All the Mark V's are Japanese made. The stocks fit so perfectly its almost as if they are full length bedded. The Vanguards all have pressure points. All of them are scary accurate for what they are.
reynolds357 is online now  
Old December 16, 2013, 06:24 AM   #44
Bart B.
Senior Member
 
Join Date: February 15, 2009
Posts: 5,412
Reynolds, if you test your Weatherby's for accuracy shooting them the same way each time from a bench, they may well produce repeatable, good results each time. If you're a good enough marksman to shoot a rifle from any field position without a rest, with and without a sling, you may be able to see the difference in accuracy between barrels free floated and those with pressure points. Good marksmen can easily discriminate a 1/3 MOA difference. A good marksman can sight in accurate rifles and ammo from offhand standing on their hind legs, and not using a sling, with one shot at 100 yards.
__________________
US Navy Distinguished Marksman Badge 153
Former US Navy & Palma Rifle Team Member
NRA High Power Master & Long Range High Master
NRA Smallbore Prone Master
Bart B. is offline  
Old December 16, 2013, 04:37 PM   #45
reynolds357
Senior Member
 
Join Date: December 10, 2012
Posts: 2,514
Bart, I am good shooting from a bench rest. I am good shooting from prone position using a bag. I am not worth a flip shooting standing, kneeling, or prone with a sling.
Bart, I am sure you are right about free floating, BUT free floating these rifle may open up a can of worms I dont care to deal with in hunting rifles that are already 1/2 to 3/4 MOA rifles. I have floated one WBY Mark V for one of my friends. It immediately went from being a tack driver to a pile of crud. I then had to put pillars in and glass bed the rifle. After that, it shot as good as it did pre-floated. I guess what I am saying is that for me, the Wby's are good enough out of the box. To help them out a little, I very welll might end up having to do a whole lot.

Last edited by reynolds357; December 16, 2013 at 04:43 PM.
reynolds357 is online now  
Old December 16, 2013, 06:10 PM   #46
csmsss
Senior Member
 
Join Date: October 24, 2008
Location: Orange, TX
Posts: 2,986
Quote:
The "blood groove" in the spine of a knife adds rigidity without making the knife heavier
It does nothing of the kind. What it actually does is sell knives to folks who think blood grooves (the correct term is fuller) are way cool because some military knives/bayonets have them.
csmsss is offline  
Old December 16, 2013, 06:19 PM   #47
Bart B.
Senior Member
 
Join Date: February 15, 2009
Posts: 5,412
Reynolds, it's my experience that free floating a barrel that ends up shooting less accuracy is caused by poor bedding around the receiver in the first place. Epoxy bedding the receiver made all 6 rifles I treated this way shoot groups about half the size of what they did before.

This is one reason why some rifles shoot off rests atop a bench more accurate with a pressure point under the barrel at the fore end's tip.
__________________
US Navy Distinguished Marksman Badge 153
Former US Navy & Palma Rifle Team Member
NRA High Power Master & Long Range High Master
NRA Smallbore Prone Master
Bart B. is offline  
Old December 16, 2013, 09:34 PM   #48
reynolds357
Senior Member
 
Join Date: December 10, 2012
Posts: 2,514
But for non-competition rifles that are not going to be shot at extreme long range, sometimes its just not worth the aggravation of doing a good bedding job.
reynolds357 is online now  
Old December 17, 2013, 06:13 AM   #49
Picher
Senior Member
 
Join Date: December 14, 2004
Location: Maine
Posts: 2,889
Bart: In my recent post discussing bedded barrels and free-floated actions, I wasn't referring to a barrel's heat that may not change inherent accuracy, but by bedding a tapered barrel in a stock, heating elongates a tube, so if tapered, and tightly bedded, there may be a tendency for the barrel to move in the bedding, even slightly. There's also a tendency for stock pressure from slings or various rests to affect barrel vibrations and POI.

My point is that free-floating sporter barrels and properly bedding the receiver minimizes POI variations. A rifle that shoots half-inch groups, but exhibits 2" POI variations is not as good a situation for a hunting rifle as a rifle that shoots 1" groups at the same POI year-round (atmospheric and other variations not considered).
Picher is offline  
Old December 17, 2013, 10:02 AM   #50
old roper
Senior Member
 
Join Date: June 11, 2007
Posts: 1,108
This is older article from PS magazine. I've had couple builds that Mike done for me.


http://www.bryantcustom.com/articles/accuracy.htm
__________________
Semper Fi
Vietnam
VFW
old roper is offline  
Reply

Tags
free-float barrel , weatherby vanguard

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 11:17 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
This site and contents, including all posts, Copyright © 1998-2014 S.W.A.T. Magazine
Copyright Complaints: Please direct DMCA Takedown Notices to the registered agent: thefiringline.com
Contact Us
Page generated in 0.13433 seconds with 7 queries