We have to find out - casting a barrel in concrete
- Thread starter davidjoe
- Start date
The best and cheapest route is to find a young shooter about to work on his Master's thesis and have him conduct the experiment using other people's money. I personally think the results will be far less exciting than you can ever imagine. Besides, how can you isolate or identify all of the variables? And lets imagine that it shot a world record - 10 times in a row. What then?
Agree...."all the variables," is key phrase. I like what Jackie mentioned in post #9. If a railgun with 1.450 barrel can't get answers, then build a rail with 2-3 inch barrel and barrel block it. Much easier than a huge block of concrete.
However, keep in mind that no two loaded rounds are ever identical. Brass, bullets, primers, powder, neck tension, etc. will slightly vary shot to shot. I produced a Smokeless Powder article a few years ago after research with several folks who actually manufacture powder. The additive packages vary from 5-10% and higher on some formulations. The additives are not always uniform within the entire mixture. If you have 30 grains in two different rounds, it will never be identical or produce identical results. Probably the most accurate powders are what is currently used in benchrest competition (N130-133, LT30-32, and a few others). The reason is because they have a minimal amount of other additive they don't need...ie, flash suppressant, and a host of other things that the military might use. There's up to 40 different materials used in smokeless powder. Just my two cents, but completely stabilizing a barrel with no shooter, may not yield one-hole groups as often as we think!
Infrequent Shooter
Gold $$ Contributor
that would be a funny sight,,,, all shooters showing up at matches w the their latest concrete rifles!!
gaintwist
Silver $$ Contributor
You have that much lead? And a way to melt it all?
[
Negative. Well, some of my F-Open rifles have technically been known to accomplish this. But I’ll need to gear up on equipment that keeps the molten lead close by.
Negative. Well, some of my F-Open rifles have technically been known to accomplish this. But I’ll need to gear up on equipment that keeps the molten lead close by.
dc.fireman
Sling & Irons!
Casting Sand:
dellet
Gold $$ Contributor
Whether you use concrete or lead, what you might consider is casting something like a 3 inch sleeve, with an 1 1/8” bore. Possibly threading the muzzle end so the barrel could be glued and threaded in. More or less making a large barrel liner.
Are you familiar wIth Franklin Mann, “The bullets flight from powder to target” from 1909?
His “Shooting Gibraltar” was about 6” tall with 40” buried down to bedrock, about 3-4000 pounds. The shooting rest mounted on top was a fixed steel rail, target aligned with the rail. Barrels were attached to a concentric chamber. Barrels were fitted with a bushing to insure that they were the correct diameter for the rail. His different tests are chronicled in the book. This was actually the inspiration for the “Mann Accuracy device” used by the U.S. military.
One thing that the barrel in the rail allowed was measuring the amount a of twist transferred from the bullet to the barrel. Another was locking the barrel down and comparing shots fired as the barrel was rotated 90*.
Probably one of the most interesting tests was his brother shooting a 10 shot group from a rickety farm table and make shifts rests, then mounting the same rifle in the Shooting Gibraltar. Groups were about 1/4” difference in size, edge going to the human shooter on the crappy rest.
If you do this test, it’s would be real interesting to do something similar. Same barrel free and in cased.
Are you familiar wIth Franklin Mann, “The bullets flight from powder to target” from 1909?
His “Shooting Gibraltar” was about 6” tall with 40” buried down to bedrock, about 3-4000 pounds. The shooting rest mounted on top was a fixed steel rail, target aligned with the rail. Barrels were attached to a concentric chamber. Barrels were fitted with a bushing to insure that they were the correct diameter for the rail. His different tests are chronicled in the book. This was actually the inspiration for the “Mann Accuracy device” used by the U.S. military.
One thing that the barrel in the rail allowed was measuring the amount a of twist transferred from the bullet to the barrel. Another was locking the barrel down and comparing shots fired as the barrel was rotated 90*.
Probably one of the most interesting tests was his brother shooting a 10 shot group from a rickety farm table and make shifts rests, then mounting the same rifle in the Shooting Gibraltar. Groups were about 1/4” difference in size, edge going to the human shooter on the crappy rest.
If you do this test, it’s would be real interesting to do something similar. Same barrel free and in cased.
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How about for keeping weight down......Place a thin aluminum tube
over the barrel and pour in some expandable foam ?? Test would be
to try different foam weights such as a 2 lb. against a 4 lb. etc, etc, etc....
Maybe start with a minimum of a 2" diameter tube or whatever diameter
would clear high ring mount's. For that matter, the tube does not need
to be round ??
over the barrel and pour in some expandable foam ?? Test would be
to try different foam weights such as a 2 lb. against a 4 lb. etc, etc, etc....
Maybe start with a minimum of a 2" diameter tube or whatever diameter
would clear high ring mount's. For that matter, the tube does not need
to be round ??
If we are trying to learn anything here for F-Class shooting, it is paramount that whatever you do, consider the dissipation of heat. When shooting 5, or especially 10-20 consecutive shots, the barrel must not build excessive heat. The repeatability shot to shot will go away the hotter the barrel gets. Almost anything you try to encase the barrel in will retain heat. Won't call any names, but many have experienced this with carbon wrapped barrels. The heat must escape for repeatability. A large diameter steel barrel like a railgun can dissipate heat, especially through the aluminum barrel block. My temp gun has always shown proof that the barrel block soaks up heat and keeps the barrel at a fairly stable temp, unless shooting in 100-115F like we have at times. Lots to think about before pouring lead and cement!
To make this happen with lead or concrete I think you would need a mechanical bond between the barrel and the lead/concrete. Some type of course threads cut into the outside of the barrel, or some thing similar. One of the posters here mentioned wires in the concrete mix. I have never seen that but have cast nylon fibers in the mix on many occasions. Maschmeiers brand name of this type of mix is Nycon, and it works pretty well for cracking. It was first designed for missile silos for the air force. Our local building dept was faxed the specs and approved it for use in local buildings the same day. If you are going to do this don't use Sakrete, use something that is strong, we poured concrete every day for years and made precast concrete products for architectural uses. Our mix was 8000psi almost every time we tested it, I doubt the bags at the depot are 2000PSI.
CharlieNC
Gold $$ Contributor
I'm wondering about any real world understanding / applicability?
Not sure what you are asking? Applicability of original idea with concrete block?? Or heat dissipation?
I’d say hopefully yes on understanding but no on applicability, at least as far as a gun like it, per se, is concerned.
The idea on a barrel that cannot move, especially on an at-home set up where I can pick and choose truly dead calm conditions, is to isolate bullet and velocity differences as the only real variables in group size, and see if we are already “there”.
When we shoot a .15” inch group, how do we know that those same bullets by themselves weren’t capable of shooting a .05” group? In theory it would be unfair to let an unlimited BR rifle, say a 70 pounder, into the light gun class, and we know it would get protested. Doesn’t mean it would win, but it cannot be used to attempt to try to win as the thinking is that it has an advantage, otherwise it would be allowed.
If they are correct in BR that weight is an advantage, then the “limit” of the advantage is that point where the gun no longer degraded group size, only bullet consistency and velocity mattered.
The totally neutral gun that didn’t “color” the outcome of shots is the question. What does it look like? Does it already exist? It would only be a happy coincidence if the totally neutral gun was something we could carry around without causing a hernia.
This is basically an extremely rigid barrel without a barrels’, as all cantilevered objects’, tendency to whip and then bounce up and down, as well as to vibrate in other directions pre-exit.
There isn’t any “spring-like” bending energy stored up in this barrel (waiting to come out of equilibrium) because of gravity, as it would sit on a rest of some kind. Cantilevered designs are generally sought out for some aesthetic or dual-role purpose, but we don’t typically seek them out for intrinsic qualities. (We group-learned not to climb out on tree branches at our peril, and the strongest, longest lasting structures we have ever built are the pyramids which are geometrically the opposite shape of a cantilever, these being some of the thought processes behind the “cube-barrel”).
Rigidity alone though, won’t tell us whether muting recoil makes a positive difference. That’s the other benefit of all the weight. If we had a light weight but ultra rigid barrel it would still recoil unless in a machine rest. A true machine rest that might stop this, is likely no more portable than this concept, and a lot less compact, and they are still not able to fully dampen the barrel end to end because that is not how they attach to the gun.
If I were to take a fresh .284 Fclass gun and shoot it beside this “thing” with ammo from the same box, and the groups of one where consistently different from the other, we could surmise that the difference isn’t because of the ammo, if I alternated guns with the same ammo box. If the big gun grouped worse than several F-Class rifles with several types of ammo, then we might not know what the problem is, but we do know that all that mass doesn’t save the group size.
If it shoots better than the Fclass guns, we still may not know exactly why that is, but we at least know that the mass and rigidity do not combine to make it shoot worse. Then the question is how different is it. Is it enough to try to figure out. Next questions are what can we slice off this slug and not see a difference, and so on.
jackieschmidt
Gold $$ Contributor
Wouldn’t it be a real “bitch” to go to all of this trouble only to find you had what us Benchrest Shooters call a “mediocre” barrel.
DirtySteve
Gold $$ Contributor
Just a thought. I ain't very smart but here it goes. Could you cast a cement block with a hole in the center then glue the barrel in using Marine tex or something similar.. Same could be done if you go the lead route with out over heating the barrel...
Edit: You can buy cannons with out ATF approval so I think there are no legal issues. Kind or like an over sized bench rest rail gun.
Edit: You can buy cannons with out ATF approval so I think there are no legal issues. Kind or like an over sized bench rest rail gun.
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