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We have to find out - casting a barrel in concrete

davidjoe

An experimental gun with experimental ammunition
Gold $$ Contributor
As to the effects of nodes, harmonics, recoil etcetera, on accuracy, over the years, a few of us here have invoked the hypothetical rifled cube of steel as a thought platform for envisioning the advancement of certain propositions about the physics involved in precision shooting.

I don’t want to repeat an experiment that is already documented, but I have the space, curiosity and materials to sacrifice a barrel by casting it in hundreds of pounds of concrete such that it will be relatively immovable, in the name of science, shall we say.

The thinking here is that the muzzle and tenon would protrude from a casting of rebar-reinforced concrete (wheeled) “sleeved” so thick and heavy (maybe 1,000+ pounds) that harmonics and possibly measurable recoil are completely defeated, to see what affect this has on group size and all facets of load development. This is as close as I’d be willing to try to get to the rifled cube, and my thought is that in the absence of wind all there can and will be is purely vertical stringing, save for increased or decreased spin drift if slightly dependent on velocity.

Questions I have:

Is this already a known outcome from a similar experiment having been done?

Is this mechanically unsafe as a proposition, or afoul of any legalities I have not thought of?

What is the best way to construct such a unitized sleeve such that the barrel never becomes loose?

The first rule in concrete work is that - it cracks, so naturally, how do we stop that?

If the barrel truly mimics a snake swallowing an egg when fired, how much reinforced concrete is needed to either suppress that tendency down to nothing, or be sizable enough so as to absorb that tendency for a 1.25” without ill effect? (We know that a gear train set in concrete and running for decades hasn’t cracked a certain block).

What else should be a consideration? A .284 was the thought here.
 
As to the effects of nodes, harmonics, recoil etcetera, on accuracy, over the years, a few of us here have invoked the hypothetical rifled cube of steel as a thought platform for envisioning the advancement of certain propositions about the physics involved in precision shooting.

I don’t want to repeat an experiment that is already documented, but I have the space, curiosity and materials to sacrifice a barrel by casting it in hundreds of pounds of concrete such that it will be relatively immovable, in the name of science, shall we say.

The thinking here is that the muzzle and tenon would protrude from a casting of rebar-reinforced concrete (wheeled) “sleeved” so thick and heavy (maybe 1,000+ pounds) that harmonics and possibly measurable recoil are completely defeated, to see what affect this has on group size and all facets of load development. This is as close as I’d be willing to try to get to the rifled cube, and my thought is that in the absence of wind all there can and will be is purely vertical stringing, save for increased or decreased spin drift if slightly dependent on velocity.

Questions I have:

Is this already a known outcome from a similar experiment having been done?

Is this mechanically unsafe as a proposition, or afoul of any legalities I have not thought of?

What is the best way to construct such a unitized sleeve such that the barrel never becomes loose?

The first rule in concrete work is that - it cracks, so naturally, how do we stop that?

If the barrel truly mimics a snake swallowing an egg when fired, how much reinforced concrete is needed to either suppress that tendency down to nothing, or be sizable enough so as to absorb that tendency for a 1.25” without ill effect? (We know that a gear train set in concrete and running for decades hasn’t cracked a certain block).

What else should be a consideration? A .284 was the thought here.
Interesting concept to explore! Dive in and ascertain the thermal characteristics of the medium you want to use. Decide from there if it looks viable to proceed.
My gut tells me to look at a hydrostatic suspension where the pressure could be controlled to a finite amount, therefore negating any non controlable values of a concrete encapsulation.
You got a boatload of data ahead to explore. Good on ya.
 
I'd say the only way to prove or disprove anything would be by first factually demonstrating a measurable deflection, then demonstrate a measureable cancelation of the deflection.

Tall order. To my knowledge, no one has managed to achieve the first step yet.

And suppose you succeed and the result is actually worse.

Edit to add, if you REALLY want to play around with the dampening idea, why not start with a bore liner? You could use any media you wanted to surround it with provided it could contain the pressure.
 
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When I first built my Rail Gun back in the late 1990’s, I encased the 1.450 diameter straight barrel 100% in a 3/16 thick stainless Tube. The OD of the tube was around 2 1/4 inches. The ID of the tube allowed for about a 1/8 thick layer of pourable Devcon which deadened the barrel. The only thing that stuck out of the sleevewas the barrel tenon.

It was a lot of work, but it shot good enough to win the 2000 100 Yard Unlimited Nationals. I also shot a personal best . .211 agg at a Region Championship, which was Five 10 shot groups.

I had to tune it just like any other barrel. I ceased doing it because the amount of work involved simply was not worth it.
 
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Sounds like it has been tried.

 
Barrel vibration is a good thing if you consider positive compensation to minimize the effect of velocity differences, as apparent when conducting a ladder test. From a potential real world application standpoint a better understanding of the frequencies and amplitudes plus the causation in order to optimize solutions is interesting.
 
Knock yerself out.
Differential thermal expansion and the insulating effect of concrete won't be kind to your experiment.
There are ways to alter concrete to make it more flexible to minimize cracking, but I suspect that'd be the least of your troubles.
 
I have been thinking about the lead idea. I could handle the volume of lead contained by say a four or five inch pipe, and then cast that whole slug in concrete. Gains most of the benefits of the build efficiencies of large quantities of concrete, without its brittleness in the most important areas. Lead is the antithesis of vibration transmission, as far as affordable solid mediums go.
 
I have been thinking about the lead idea. I could handle the volume of lead contained by say a four or five inch pipe, and then cast that whole slug in concrete. Gains most of the benefits of the build efficiencies of large quantities of concrete, without its brittleness in the most important areas. Lead is the antithesis of vibration transmission, as far as affordable solid mediums go.
Just thinking about what the 600 degree molten lead will do to the barrel. It is hot enough to have an effect on the metallurgical properties of the barrel not to mention any stresses induced during cooling.

How about cerrosafe? It's melting temp is probably no higher than the barrel might get buring fireing.
 
Just thinking about what the 600 degree molten lead will do to the barrel. It is hot enough to have an effect on the metallurgical properties of the barrel not to mention any stresses induced during cooling.

How about cerrosafe? It's melting temp is probably no higher than the barrel might get buring fireing.

My thought on the lead, kind of out of necessity, was adding a little at a time. Hopefully letting the barrel dissipate the heat kind of like we can touch hot aluminum foil but not an iron skillet handle of the same temp. The lead won’t remelt in firing but the one you mention sounds like it would.
 
Just thinking about what the 600 degree molten lead will do to the barrel. It is hot enough to have an effect on the metallurgical properties of the barrel not to mention any stresses induced during cooling.

How about cerrosafe? It's melting temp is probably no higher than the barrel might get buring fireing.
Jerry Hensler put his barrels in a tube with Cerrosafe. That is where I first got the idea, only I used Devcon.

Charles Huckabe used to wrap strings of those lead tape weights they use on golf clubs around his Rail Gun’s barrel.
They sure shot well.
 

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