Dimpling a barrel

[SR-47]

I thought I would post some pictures of a test I did on 2 stainless barrels they are both from the same lot the only difference is that one has been painted black.

in this test I measured the deflection of a stock barrel against a dimpled barrel using 50 pounds of weight hanging from each barrel in a cantilevered barrel fixture that simulates the barrel in a upper receiver

sorry the scale is upside down


stock barrel at rest in test fixture

stock barrel with load

dimpled barrel at rest in test fixture

dimpled barrel with load


stock barrel weight 2LB .4oz

dimpled barrels weight 1LB 9.6oz

thats a difference of 195g or 6.8 oz

here they are side by side

I have had no complaints about accuracy
no complaints at all

Marvin

[AEuropa]

Belmont, to be clear, my post was not aimed at you directly. It was just an observation about this thread in general. And you don't need to convince me of the merits of fluting; my Afghan barrel is in the USPS system on it's way back to me from being fluted by Noveske. Based on my own research, I personally believe that it is beneficial (depending on the intended use of the rifle), however I try to steer clear of making absolute statements regarding a subject that I have not personally tested or, at a minimum, seen test results about.

Marvin, thanks for the data. I would be interested in seeing a similar test with 2 barrels of equal weight, one fluted/dimpled and one with a lightweight contour, to see what the results would be. That seems to be the primary argument when it comes to stiffness.

- Alex

[Robb Jensen]

Marvin dimpled my BCM SS410 from the gas block forward. I think it turned out great. I didn't have the midsection dimpled because I had it turned down to .650" by WAR Rifles a while back. I think the next one I'll have done is my Colt 10" SBR barrel.

[SR-47]

Marvin, thanks for the data. I would be interested in seeing a similar test with 2 barrels of equal weight, one fluted/dimpled and one with a lightweight contour, to see what the results would be. That seems to be the primary argument when it comes to stiffness.

- Alex

If I were to remove the same weight of material from all the barrels the dimpled barrel will give the best results it will be more rigid than the lighter contour barrel and have more hoop strength than the fluted barrel and I would argue that it has the potential to be more accurate

[Evil Bert]

@Marvin

I am confused by those images. The dimpled with load appears to flex or be less rigid than the non-dimpled barrel. Am I understanding the images? Can someone please explain?

[orionz06]

@Marvin

I am confused by those images. The dimpled with load appears to flex or be less rigid than the non-dimpled barrel. Am I understanding the images? Can someone please explain?

The dimpled barrel deflects more than the non dimpled barrel.

[Brahmzy]

Good grief folks, this isn't rocket science.

[decodeddiesel]

Good grief folks, this isn't rocket science.

No, but it is science of materials.

[Evil Bert]

The dimpled barrel deflects more than the non dimpled barrel.

That is what I thought, but there are people and gunsmiths/mfrs that claim it increases accuracy, but as I understand it, deflection decreases accuracy. These pictures support that with the dimpling.

[montrala]

That is what I thought, but there are people and gunsmiths/mfrs that claim it increases accuracy, but as I understand it, deflection decreases accuracy. These pictures support that with the dimpling.

There is one picture missing. One with barrel that is not dimpled but has some weight like dimpled. Because dimpled or fluted barrel are expected to be stiffer and more accurate that plain barrels of same length and mass, not same length and diameter.