Fluting and chambering a barrel

[Tiff]

Anyone else able to answer my question?

J.

No reason why they cannot be as deep/wide as you want, provided it's safe. I'm fairly sure I' ve had flutes nearer 6mm deep in the past.

[BarrelBoy]

Out of interest BB, could the flutes be cut any deeper than 2.5mm, if the barrel was thick enough to stay within the safe parameters?

Yes u can have deeper flutes depending on the thickness of your barrel what caliber it is i allway like to be on the safe side

[AT308]

Here is some intresting reading on fluting, its worth a read before making any decisions.

Here is a snipit from the article from this link!!

 

http://precisionrifleblog.com/2014/11/18/rifle-barrels-what-the-pros-use

An article written by Tom Beckstrand in the 2013 edition of SNIPER magazine summarizes some tests that Accuracy International performed to determine whether fluting a barrel affected accuracy. Here is an excerpt from that article:

One design change that resulted from AI’s exhaustive accuracy testing and development of the PSR [Precision Sniper Rifle] is the removal of flutes from the barrels.

Engineers at AI decided to isolate the barrel flutes to see what impact they had on accuracy. The engineers attached a laser to the rifle’s receiver, another to the barrel, and a third to the scope. All three dots were zeroed at the same point, then they started shooting the rifle. They discovered that, no matter which fluted barrel they used, the dots would diverge as the barrel heated.

The dots from the devices mounted to the scope and the receiver would stay in place, but the barrel’s device would manifest a point-of-impact (POI) shift.

The POI shift from the warming barrel greatly diminished when they used barrels without flutes.

Engineers determined that the flutes never heated evenly, causing the POI shift.

I hope the results of this test gain wide circulation through the sniper and long-range shooting communities to help eliminate some of the ignorance that surrounds the perceived advantages of barrel flutes. Flutes are great for shaving weight, but this is the first test I’ve heard that provided empirical data detailing what happens when the barrel is fluted. This should be the death of the “they cool a barrel faster, so they’re more accurate” argument, listed among flutes’ virtues. Our goal is and should always be to mitigate the effects of heat; fluting exacerbates it.

[meles meles]

The barrels of the more accurate tank guns, rifled or smoothbore, are always clad with a thermal jacket to ensure even distribution of heating or cooling effects. It's not the heating or cooling per se that causes the problem, but an imbalance of it from one point in the barrel to another. A jacketed barrel can achieve a dispersion of less than 0.2 mills between the first, cold barrel shot to the fifth shot (by which time the barrel is rather warmer). An unjacketed barrel achieves nothing like that accuracy. Fluting will almost certainly exacerbate the problem: though it does aid in cooling by increasing the surface area available for radiation and convention, that enhanced cooling will probably be both uneven, as AI discovered, and thus lead to differential stress relaxation in different parts of the barrel causing t to expand, shrink and / or twist inconsistently.

[gbal]

Fluting removes metal,and Therfore weight from a barrel. LIghter barrels heat up faster,and the effect is sht dispersal increases.

There seems no consistent consistent evidence that 'increased surface area' by fluting promotes cooling of an least equal amount to compensate for the lightness effects.Indeed there may not be much increased area,though fluting can vary-with effects on both surface,weight and probably,stress.

Then there are the stress/irregular heating effects others have described.

Perhaps the relative rarity of fluted barrels in Bench Rest or 'precision shooting' indicates that different disciplines have found no advantage for accuracy/precision,though undeniably lighter for stalking etc.

 

gbal

[22lrman]

Very interesting AI article. It appears to make some sense. With no wind, I would expect the top side of the fluted barrel to cool quicker than the lower side, as heat rises away from the barrel faster on the top side. The rate of cooling being accelerated by the increased surface area of the fluting. I wonder if the movement was measured as upwards (cooler top side - hot lower side.).

With a side wind the same effect again with the faster cooling side against the wind. I assume (i know i shouldn't !) that the fluting increases the rate of cooling faster than the heat can equalise (move) from the hot side of the barrel, and the result is the temperature difference and hence barrel movement.

Assuming again that the thermal resistance (resistance to the movement of heat) within the barrel does not change after fluting (the material has not changed). And the rate of cooling is increased by the fluting. Then the difference betweeen rate of cooling at the cooler side, and rate of thermal equalisation of temperature difference will be increased. Hence more thermal differences and more bending.

 

Phew, does that make sense to anyone?

[Jamie]

Yes u can have deeper flutes depending on the thickness of your barrel what caliber it is i allway like to be on the safe side

Thanks BarrelBoy and Tiff for answering my question

[bewsh]

Interesting- does anyone have up to date estimates for a Sako or a Remington -whatever-factory rebarrel....?

 

gbal

 

have a look on US eBay

used to be 100's of unfired remington factory barrels for sale for pennies

they have been pulled for custom jobs and are redundant

 

if you could find someone willing to ship, you could very well grab a bargain

 

 

http://www.ebay.com/sch/i.html?_from=R40&_sacat=0&_sop=1&_nkw=remington+rifle+barrel&_dcat=73949&rt=nc&LH_ItemCondition=3

[bradders]

So the other night I decided to have a quick go at fluting to see how my new cutter performed

 

This was to just prove to myself, and now have to just order a radial head and some angle plates and clamps and we're off :-)