We have to find out - casting a barrel in concrete

[dryhumor]

This should work.

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Put a barrel in the middle, place something like a Sorbothane tube or sleeve around the barrel, fill with your favorite concrete.

Not certain about the thermal qualities of Sorbothane though, but I would think it would mitigate vibration from entering the concrete.

 

[Knotwild]

Too many uncontrollable variables. I see the experiment raising more questions that giving definite results. I wish you luck and I will be one of the first in line to observe the results.

 

[davidjoe]

For a couple of days I have stared at an apparent fork in the road. What weight barrel to use. I have a 1.4” 6XC for a Bat L 2.0 inch SS action, low round count, which avoids the possibility of bad barrel. I had originally thought a 1.25” new barrel, and then a third option arose.

Is the premise not better suited to seeing what improvement could be brought to bear on a familiar quality, such as a barrel like a new heavy Palma contour Krieger 5R? The 1.4” straight 6XC is so stout that however it groups, I think the tendency would be to assume the groups could be expected,

A straight 1.25” 7 mm is meaty enough shoot either in the teens, or, as Jackie mentions, shoot in the 3 to 4’s its whole life.

I do have a Palma or heavy Palma contour Krieger .308. These are both fairly near a Sendero’s profile, to the plus side.

Such profiles are considered of marginally adequate rigidity for Fclass, but they are very well made barrels. I do not think the uniformity or steel can be faulted, just the weight. The profile was suited for big rings and prone sling guns.

Suffice it to say that such a barrel is not chosen to try to shoot Benchrest groups, and I don’t see results like that in any of the several I have used. I think it would be very interesting to see if a such a barrel, with a typical 700 type action, could be made to shoot true one hole groups, lets say the teens and better, and further that it doesn’t walk the shots sideways at least, when heated because it is so securely captured.

An advantage of a Sendero-ish weight barrel is that we can generally relate to what they do. In an instant group pics will be identifiable as exactly the same as either a factory varmint, an FTR, or hopefully, a very, very good small bore BR gun, even though it won’t be small bore (.308 Win). Am I trying to convince myself or does it sound logical. I could do any.

Secondly, by chance did the project 20 years ago disappoint them because it is hard to aim a gun like these? I’m looking ahead. That’s a problem. I could always move the target around, but I’d like to know if point of aim ever shifted, even if a couldn’t do anything about it.

 

[dgeesaman]

Some random thoughts. Apologies if this is already-trodden ground.

- Sand has amazing vibration dampening properties - think of how well a pillow of sand works to cushion a falling egg in the physics class 'egg drop' competition. While concrete and packed casting sand are infinitely more rigid, perhaps it's worth conducting the test first in a dry sand bed before sealing it into concrete.
- Barrels definitely change with shot count, so makes sense to choose a caliber that is very easy on barrel bores so that you can use the same barrel mounted the usual way, then cast in sand and/or concrete so your results are as comparable as possible across the progression of tests. Ideally there would be a way to come back to the starting point and repeat the baseline tests.
- I assume you'd build a new tune with each configuration. It makes little sense to test without an optimized tune.
- Metal-filled two-part epoxy might do nicely to bond a barrel to a heavy concrete slab or something and with metal filings it can actually be somewhat conductive.
- considering that the shock wave energy of a standard barrel is pretty well agreed to be significant (even if it's hard to predict with mathematical certainty), is there a way to build the concreted barrel so that the shock waves have no way to reflect back inward before the bullet has exited?
- Likewise, with barrels expanding under the internal pressure ~50,000psi, it will put surrounding concrete in tensile stress, which is concrete's weakness. It seems wise to reinforce heavily immediately around the barrel, perhaps spiral-winding steel reinforcement there. Also any ring tests for concrete integrity before/after the test to are crucial to confirm if the shooting caused cracks / looseness to develop within the structure.

 

[davidjoe]

This is what I am thinking. Between now and casting the barrel in concrete in a round form, I plan to cast the barrel in a cardboard tube with this fiberglass reinforced filler, then peel off that tube, then cast it in high strength concrete with the coil and some straight pieces.

 

[SKWERLZ]

Not certain, but I think the concrete might shrink away from the barrel. If a large recoil disc were used at the tenon, and a large threaded disc were used on the muzzle end , some tension could be put on the barrel, preventing movement. Just a thought

We used to use a lot of non shrink grout for lifting houses, slabs and foundations.

Adding shredded fiberglass or carbon fiber to the mix could be interesting
As would a carbon wrap on the concrete jacket.

 

[perazziguy]

I think you need to go and shoot, David...

 

[3-300s]

Pour it full of 2850 stycast.
tough stuff, heat or cold doesnt really effect it.
adheres very well , doesnt shrink much when curing...
or wrap in glass cloth with stycast as the resin...
Its made by loctite and worth the time to look at the specifications.

 

[davidjoe]

I think you need to go and shoot, David...

Yes! I’m at the range. First one in new group after rest always goes high. I think because the barrel can move lol.

Really like this new Spuhr quick detachable mount. We have our club championship 600 Sunday. I think it will be this gun and either 190 A-Tips or 195 Bergers, .284 Win. Single digit wind predicted.

 

[Jonnyofalltrades]

BTW, I don't think lead will stick to stainless, solder doesn't anyway.

Not so sure about that. I solder stainless quite often. That's with low temp silver solder, not lead/tin, but still.
The outside could be tinned first, before the pour.
I think with that big of a quantity of lead, weird stuff is going to happen while it cools. No scientific knowledge to back that up, just a feeling.

 

[CharlieNC]

If you want to stop muzzle vibration, mount the rifle in a barrel block installed at the muzzle. Then slide the mounting point along the barrel to allow for numerous various degrees of vibration. This would allow shooting with no dampening as a control trial as often as desired. Remember the bullet exit time is only around 1.5 milliseconds and muzzle amplitude of only several thou; the cantilever vibrations don't occur until the bullet is done.

 

[davidjoe]

If you want to stop muzzle vibration, mount the rifle in a barrel block installed at the muzzle. Then slide the mounting point along the barrel to allow for numerous various degrees of vibration. This would allow shooting with no dampening as a control trial as often as desired. Remember the bullet exit time is only around 1.5 milliseconds and muzzle amplitude of only several thou; the cantilever vibrations don't occur until the bullet is done.

What would that barrel block at the muzzle attach to? My longest F-Class stocks are the Manners F-Class Comp stocks and their fore ends still stop less than halfway down the barrel.

 

[CharlieNC]

What would that barrel block at the muzzle attach to? My longest F-Class stocks are the Manners F-Class Comp stocks and their fore ends still stop less than halfway down the barrel.

It would attach just like a concrete covered barrel, just a more convenient option to study harmonics.

 

[CharlieNC]

Thinking about this a bit, using a barrel block and sliding the barrel from receiver to muzzle would be an excellent basis to further define the critical harmonics and a means to adjust it for optimum positive compensation:

a. In Vaughn's book he analyzed charge weight ladders (which exhibits a flat spot or even a reversal in vertical poi), and I used his procedure to evaluate my ladder results as well. In all cases the frequency is associated with the speed of sound along the length of the barrel. The protrusion length affects the actual frequency and amplitude of vibration. All this based on the target poi movement.

b. When shooting various barrel lengths protruding beyond a mounting block, a charge weight ladder at each could be analyzed to determine the effect of the resulting muzzle harmonic frequency as determined by the target. Less protrusion should result in higher frequency and lower amplitude.

Ultimately the challenge becomes finding a "setting" whereby the frequency and amplitude of the placement "exactly" offset the ballistiic effect of the charge weight on velocity and poi.

 

[jackieschmidt]

The barrel block at the muzzle has already been tried as well. On a Rail Gun chambered in 6PPC.

I know Jerry Hensler was playing with it, and I think Mike Bryant did as well. From what I remember, it did not shoot that well.

I looked on some shelves in one of our buildings and found one of the barrels I encased in the Stainless Steel Tube. Also, this is the only picture I have of my Rail Gun with that tube encased barrel. It shot very good, but was just too much trouble.

 

[CharlieNC]

The barrel block at the muzzle has already been tried as well. On a Rail Gun chambered in 6PPC.

I know Jerry Hensler playing with it, and I think Mike Bryant did as well. From what I remember, it did not shoot that well.

I looked on some shelves in one of our buildings and found one of the barrels I encased in the Stainless Steel Tube. Also, this is the only picture I have of my Rail Gun with that tube encased barrel. It shot very good, but was just too much trouble.View attachment 1611739View attachment 1611740View attachment 1611741

Jackie I would not expect a block at the muzzle would shoot well as totally suppressing the barrel harmonics would virtually eliminate the possibility to tune via positive compensation. There should be a mounting sweet spot between the muzzle and receiver, which would be an interesting study.

 

[perazziguy]

Yes! I’m at the range. First one in new group after rest always goes high. I think because the barrel can move lol.

Really like this new Spuhr quick detachable mount. We have our club championship 600 Sunday. I think it will be this gun and either 190 A-Tips or 195 Bergers, .284 Win. Single digit wind predicted.

Then that settles it, you definitely have to find out! Good shootin'

 

[davidjoe]

The barrel block at the muzzle has already been tried as well. On a Rail Gun chambered in 6PPC.

I know Jerry Hensler was playing with it, and I think Mike Bryant did as well. From what I remember, it did not shoot that well.

I looked on some shelves in one of our buildings and found one of the barrels I encased in the Stainless Steel Tube. Also, this is the only picture I have of my Rail Gun with that tube encased barrel. It shot very good, but was just too much trouble.View attachment 1611739View attachment 1611740View attachment 1611741

I’m curious what was inside the tube? Is that rail gun still around?

 

[Lee in Texas]

The barrel block at the muzzle has already been tried as well. On a Rail Gun chambered in 6PPC.

I know Jerry Hensler was playing with it, and I think Mike Bryant did as well. From what I remember, it did not shoot that well.

I looked on some shelves in one of our buildings and found one of the barrels I encased in the Stainless Steel Tube. Also, this is the only picture I have of my Rail Gun with that tube encased barrel. It shot very good, but was just too much trouble.View attachment 1611739View attachment 1611740View attachment 1611741

Has anyone just made a barrel that big around? That could be interesting.

 

[Longrange57]

Have Jay Young build you one of these. They make inserts for whatever size barrel you want. Can make the barrel block as long as you want it. It will be much more repeatable and have a better comparison to the setup you are currently using. Not sure a concrete block is going to get the info you want.