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Old July 7, 2013, 10:49 AM   #1
HankC1
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Barrel contour F34 or F54 fluted

Building a Mauser in 308 and want to fit a Green Mountain (Adams & Bennett) barrel from MidwayUSA. The rifle will be mostly for target shooting at the shooting range but want to be able to take it out in the field as well. I built one with F54 Chrome Moly barrel last time and it is very accurate but too heavy for field use. Is F34 barrel contour a good choice for target shooting as well or it is too light? Should I consider a fluted F54 that they offer in stainless. I really like a F44 (.725" dia) contour but they don't offer it for 308. If I add a removable weight in stock, will it serve the purpose of a heavier barrel for target shooting at shooting range? F34 (4 lb) is .65" muzzle diameter while F54 (5.25lb non-fluted) is .83" dia. Both 24" long and 1.2" dia. at receiver end.

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Old July 8, 2013, 01:42 AM   #2
Jimro
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For primarily target shooting but possible field use get the fluted F54 contour.

Approximate weight for F34 is 4 lbs. Approximate weight for F54 is 5 1/4 lbs. If the fluting shaves off more than 4 oz's then you have less than a 1 lb difference between barrels, and the F54 contour will be stiffer.

There are some folks who want their rifles as light as possible, but I find anything less than 8 lbs is a bit much on my shoulder for "target shooting."

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Old July 8, 2013, 06:30 AM   #3
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Buy a Boonie Packer Safari Sling for humping around a hunting rifle and a 1.4lb difference in weight will not be felt. I have hauled a 10lb + hunter for 16 years with one of those sling. I wear mine a bit higher than in this video but it show the basics.
http://www.youtube.com/watch?v=FGwn6Kfno7o
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Old July 12, 2013, 11:32 AM   #4
HankC1
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If I go with F54 barrel, who has wood stock for the heavy mauser barrel? Last rifle I built was on Boyd's stock which is really for sporter barrels, after opening the barrel channel, there isn't much wood around the barrel opening. Boyds stock is nice and reasonably priced. I don't want a plastics stock or expensive custom stock. I heard fluted barrel may have more distortion when barrel heat up if not stress relieved correctly. Is this still a concern today?
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Old July 12, 2013, 12:14 PM   #5
Bart B.
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Fluted barrels are no different that solid ones when it comes to them heating up. Either type not fit correctly to the receiver or made with poor metalurgy and stress relieving will move point of impact when they get hot.

If that fluted barrel is done so after the bore's rifled and it's a button rifled barrel, it may well have uneven diameters at each end of the flutes.

I think you'll be better off with a plain barrel of the same contour as a fluted one. It'll be stiffer and probably more accurate. Fluting a barrel makes it less rigid; it's stiffer before it's fluted. Removing metal by fluting takes away some of the metal that otherwise resisted its bending.
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Old July 12, 2013, 12:34 PM   #6
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Certainly some opposing ideas afloat here. I don't think you'll see any accuracy degradation in a barrel of the quality that I've seen from A&B. By that I mean the A&B are good but usually not good enough to see the razor edge accuracy being compromised by the fluting. I personally like the fluting and would use that option if it were mine. I find the heavy barrels more unwieldy as I get older and lose upper body strength but appreciate the steady hold and decreased "hot barrel shift".
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Old July 12, 2013, 06:01 PM   #7
Bart B.
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Mobuck, what makes you think heavy barrels decrease hot barrel shift?

Any decent rifle barrel, thick or thin, heavy or light, fit properly to the receiver will not shift point of impact as it gets hot. Even when shot 40 times 20 to 30 seconds apart. Or as much as 24 shots in 50 seconds as is done in some competition and they don't have any hot barrel shift. I've shot 'em all and never had any shift of bullet impact as they heat up.
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Old July 13, 2013, 06:53 AM   #8
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Hank if you heavy barrel a mauser you will have to fit the stock to it.
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Old July 13, 2013, 07:01 AM   #9
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Fluted barrels? Have at it if you like the cosmetics. But there's no evidence they contribute anything to accuracy or keeping the barrel any cooler than an unfluted barrel of the same length.
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Old July 13, 2013, 10:07 AM   #10
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True, but in this case the fluted barrel is also heavier than the unfluted barrel, given that information, it will be stiffer.

I have an F54 ChromeMoly barrel on a Mauser I put together. The first thing I did was true the reciever shoulder in the lathe. I don't believe torquing to the inner C ring is necessary, but you can buy a jig to true that surface, as well as the bolt face. Recommend truing the bolt face, especially if you reload.

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Old July 13, 2013, 07:46 PM   #11
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csmsss, fluting a barrel will let it cool faster. Some folks have measured their temperatures and a given barrel fluted will cool down about 10 to 20 percent faster depending on the number and size of the flutes.

Check out the following for some good info on fluted barrels:

http://www.snipercountry.com/article...relfluting.asp
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Old July 14, 2013, 10:00 PM   #12
Mobuck
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"Mobuck, what makes you think heavy barrels decrease hot barrel shift?"
Mostly the fact that many "sporter weight" barrels show a change of impact or stringing after as few as 3 rapid shots.
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Old July 14, 2013, 10:23 PM   #13
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I am not a barrelmaker,but I am a toolmaker with a lot of experience making chips.

My money,my barrel...If someone like Kreiger,Lilja,Badger,etc flutes a barrel,they flute it at some stage of stress relief/lapping /rifling so the fluting does no harm.
And,it is reflected in the price.

A fluted econo barrel? Well,I'm leary.If that means a finished #5 is pulled off the shelf and grooves cut,with no further stress relief or lapping,I don't like it.

No matter how sharp your cutter is,it does some cutting,and some displacement of steel....battering.

A fluting cutter ,like the old time nut splitter,or cold chiseling across the flat of a nut,will increase the bore dia by some amount.

The cutter will also wipe some steel longitudally,creating stress in the barrel.

I know how to cut pretty grooves in a barrel,but I would not buy a Krieger barrel and flute it myself.
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Old July 15, 2013, 06:00 AM   #14
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HiBC raises some points that I agree with, but I'd like to raise some other points that make you think about things differently.

Here are the questions to really ask yourself:

If a stressed barrel doesn't shoot as well as a stress relieved barrel, how can Tikka make an accurate rifle with a hammer forged barrel? Stress relieved and double stress relieved sound like really great buzzwords for barrel makers, but you can also get amazing accuracy from highly stressed hammer forged barrels.

If cutting into the outer diameter of the barrel changes the bore dimensions, will that matter enough to decrease accuracy for your purposes? AR barrels have often used taper pins that get pounded in there plenty good, and still produce good accuracy.

And one of those, "everyone knows chrome lined barrels are less accurate." fallacies, but the FN SPR A1 came with a chrome lined barrel, same twist rate as the M240B machine gun barrels also made at the FN factory, and that system has produced excellent results with the accordant long barrel life.

And lastly, are you a good enough shot to tell the difference between a .75 MOA barrel and a .50 MOA barrel?

The finished rifle has a purpose in your mind, primarily target shooting with some field work. I doubt that you are a good enough shooter to outshoot the fluted F54 barrel, I know that I am not, at least from field positions.

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Old July 15, 2013, 09:21 AM   #15
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Mobuck, and others, here's why most factory installed barrels change point of impact when they heat up.

The receiver face is not squared up with the barrel tenon threads. When the barrel torqued in, it bears hard at one point. When it and the receiver heat up, the expanding metal puts a greater stress point where that place is and that makes the barrel bend.

Some folks have squared up their factory receiver faces by turning off 5 thousandths, then putting in a .005" shim between it and the barrel so it clocks in to keep headspace correct. Such changes get rid of shots walking as the barrel heats up.

"Sporter weight" barrels are the norm in M1 and M14 rifles, yet when match conditioned, such rifles and those barrels hold zero even when fired 24 times in 50 seconds. They've been tested in machine rests and have shot sub MOA at 600 yards so stressed. And they'll shoot 1/2 MOA at 300 yards fired 10 times in 60 seconds. One 7.62 NATO chambered Garand put all 8 shots from a full clip in 40 seconds into 7/8ths inch at 300 yards when tested starting with a cold barrel.

And most sporter weight 22 and 24 inch barrels are stiffer than Palma rifle's thicker 30 inch long barrels. Those long ones are oft times shot once every 15 seconds for 20 shots and they'll shoot 1/2 to 5/8 MOA at 800 yards for the whole shot string.
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Old July 15, 2013, 04:18 PM   #16
HankC1
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Another question on fluted barrel installation. How to make sure I have the barrel fluting timed correctly when installed on receiver? How many degrees turn is typical from hand tight to finial torque and how much torque for large ring Mauser installation? This would be my first fluted barrel build! I have a F54 non-fluted 308 mauser and couple sporter weight 308 mausers. I do shoot better with heavier barrel compares to sporter barrel, I think the weight helps more than stiffness. That is why I ask if adding weight to stock will achieve a significant effect of improvement as heavier barrel. I am not a competition shooter and happy if MOA!

Last edited by HankC1; July 15, 2013 at 04:33 PM.
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Old July 16, 2013, 02:00 AM   #17
Jimro
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There is no "correct timing" for barrel fluting unless you care about looks.

The radial symetry of the fluting allows for any orientation, so just install and shoot. If you care about having an unfluted portion of the barrel at the 12 o'clock position, just have your gunsmith cut the shoulder back until that is the case before he sets final headspace.

Or if you are doing the work yourself, a standard Mauser thread pitch is 12 per inch. That means 0.083" inches travel per rotation. So if you need to move a 6 fluted barrel (one flute every 60 degrees) 30 degrees (halfway between flutes) then you are looking at making a cut on the shoulder about 0.0069" not including leaving some on for final torque. For a 5 flute barrel it would be slightly deeper, but the math is the same and your gunsmith knows how to do it.

Anyways, I'd just make sure the reciever is trued up, install the barrel and not worry where the flutes end up.

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Old July 16, 2013, 06:01 AM   #18
HankC1
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Quote:
leaving some on for final torque
That is what I was asking. How much rotation to achieve the final torque? I want the fluting (6 flutes) timed correctly for the look with unfluted land at 12 o'clock, so I anticipate that I may need to shave the shoulder a bit to do that. When building a FAL, the typical rule is hand time to 10.5-11 o'clock then I will be ready for the final torque (around 80-100 ft-lbs), FAL has 1-16 receiver thread, So I need to hand tight to a bit less than 30 degrees (11 o'clock), as calculated by (30 to 45 degrees)*12/16, when building a Mauser with a fluted barrel?
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Old July 16, 2013, 07:17 AM   #19
Bart B.
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Jimro asks if a stressed barrel doesn't shoot as well as a stress relieved barrel, how can Tikka make an accurate rifle with a hammer forged barrel?

Same way Winchester did with their hammer forged barrels used in their Model 70 .308 Win. match rifles. Those barrels had stress direction outward from the bore pretty darned equal in all radial directions. Just the opposite of a button rifled barrel with stress forces inward. Both were not much and played no part in the accuracy attainable.

Win. 70 hammer forged match barrels (available at retail) were often used in M1A and M1 match conditioned rifles in 7.62 NATO. While they were profiled the whole length to fit the rifle, their bore and groove diameters remained uniform enough to shoot good lots of M118 match ammo and handloads with Lapua D46 185-gr. bullets inside 4 to 5 inches at 600 yards. Both bullets had diameters larger than the barrel's groove diameter. No point of impact changes observed as they heated up from ambient to way too hot to touch.

On the other hand, Win. 70 hammer forged match barrels did tend to open up a bit under the flutes when so modified. The change in bore/groove diameters at the ends of the flutes did tend to degrade accuracy a little bit.
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Old July 16, 2013, 08:31 AM   #20
Jimro
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Bart B. I appreciate the info, it was a rhetorical question so that people wouldn't think "double stress relieved cut rifled barrel" was the only option for shooting tight.

Krieger and Criterion both sell excellent barrels, the only real difference is cut verses button rifling, and the enough of the Big rifle companies of switched to hammer forged barrels that they've proven those to be capable of excellent accuracy.

I'm sure you've shot with folks using Hart barrels (button rifled) to good effect, and I've shot with a shooter using a Tikka Tactical and it held every bit as good as a Rem M24. As long as the bore and groove diameter are uniform, you have a good chamber, throat, and crown, pretty much any type of barrel will shoot great.

Jimro
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