243 Winchester model 70

[hb]

.243 Winchester model 70. It has fluted barrel. Whats the significance of a fluted barrel.


Pre 1964. Limited produce

[marksman]

Basically to reduce barrel weight. Also helps the Harmonics of the bullet and reduces mirage effect when the barrel is real hot, In my humble opinion pretty ugly and useless in our scenario unless one decides to shoot it for big bore competition..

Marksman

[eljefe]

Fluted barrel in a pre 64? Was it after market or original?

[375h&h]

Fluting helps reduce weight by removing material, also aides in cooling by increasing surface area. It can also allow for a heavier barrel without adding weight. The latter two features can aide in improved accuracy.

[timmy]

Whats the significance of a fluted barrel.

The first concept one needs to discard is that the steel parts of a gun are "hard." Perhaps, compared to an eyeball, they are, but when studying the performance of a gun, steel is not very "hard." It is flexible.

There are fast photography videos of this on youtube, which can be found and watched if someone is interested. I learned about this while working on cast iron automobile engines. One quickly learns in that sort of work that a cast iron engine block is actually quite "springy" and flexible.

While working with an AK-style rifle (back in 2004, one of our presidential candidates said that one didn't need an AK to hunt. I immediately went out and bought one. Note here, the other candidate tried to renew a so-called "Assault Weapons Ban." Seldom do I trust any politician when it comes to gun rights. They must all be watched very closely to protect what freedoms we have.), the idea was to elk hunt with an AK, and I selected one with a 20 inch barrel to maximize the performance of handloaded ammunition. I calculated that, if a range of 100 meters or less was accepted, the 7.62x39 would be acceptable with the right shot.

I found a video on youtube where an AK was fired and the whole thing whipped and flopped around like a piece of wet spaghetti when fired. It was clear to me at the time that getting any appreciable accuracy out of that thin barreled rifle would be a real challenge.

So, a barrel vibrates when fired according to specific harmonics, like a spring vibrates to specific harmonic properties. Making a barrel heavier changes these harmonics, decreasing their amplitude. The idea is to optimize the barrel's vibration so that, with a certain bedding of the barrel and action and with a certain load, the bullet will leave the barrel at a predictable vibration point and thus "throw" the bullet to the same place with each shot, giving accuracy.

A heavier barrel also absorbs more heat than a thin one. Steel has stresses in it when it is made into a barrel an the application of heat will cause the barrel to bend as these stresses are heated. This heat occurs when the gun is fired. A thin barrel will heat up more quickly than a thick one, just as a half-empty cup of coffee heats up faster in the microwave than a full one does. So, a thin barrel may put its first or first and second shots near an aiming point, but as it heats, the stress points change the barrel's straightness and vibration, throwing further shots away from that given point of aim. The heavy barrel doesn't heat up so fast, so doesn't react so much when fired in succession.

One way to get a barrel that is stiff, like a heavy barrel, but light like a thin one is to machine flutes into it, somewhat like a revolver's cylinder is sometimes fluted to retain strength and make it lighter. This is like reducing a bar of steel to an "I-beam" shape makes it quite a bit lighter, yet it retains much of the solid bar's strength.

As pointed out, the flutes also increase the surface area and radiate heat to the air better than a solid surface, somewhat like cooling fins on a motorcycle engine. This reduces the effect of heat somewhat.

[Martin Clarke]

Hi Timmy,
Very informative, and yet simply explained.
Cheers.....Martin