I am not sure that a barrel maker would have any incentive to switch over. The only modifications necessary are the hook-cutter angles, and the cutter itself would need replacement more frequently.
I suppose a simple price premium could be enough. But this would definitely make a genuine dent in repeat service. In other industries which I have observed, a scenario for change like this is purely customer driven.
Your question on equipment is slightly different. A very complex gain-twist can be done easily on a sine-bar machine, but for prototyping, CNC is the way to go. Once geometry is established, manufacture could be wide spread.
I guess I should qualify the foregoing, by mentioning that a variable width groove has advantages in a high performance application, and this is one of the patent items. I am not aware of any barrel makers that know how to do this.
addendum #2... I also need to add that honing, rather than lapping, is the only way to do this.
Last edited by noel carlson; 06-21-2009 at 04:00 PM.
I knew the "debate" characterization of this thread was something of a misnomer, My answer is that you are still all throwing away that barrel following a few thousand rounds due to heat-erosion. This will make even a 416 barrel live for alot longer (I do not actually know how much longer.). The trick is to utilize a shell casing that is designed to disperse the gel. As it happens, this shell casing has approximately the same life as the barrel itself... that is a single shell casing. Is anyone tired of buying, and reworking, quality brass?
I will go to rifling geometry unless anyone has a question at this point.
How much does that shell casing cost? I'm using a product called Gun Juice. I don't know what it lays down on the surface of my bore, and I don't know if my throat and bore will last any longer. I don't shoot enough to find out any time soon. But fouling is next to nil and cleanup is a snap. I've seen velocity increase 45 fps in one barrel. But Gun Juice is applied to the bore, not entrained in the powder charge. Proceed...
*AND THEN THERE WAS GERARD, AND THAT BULLET WAS GOOD*
As mentioned earlier, engraving bands are a very old idea. By the time the second world war arrived, the design had fallen into virtual disuse in favor of "Bore-Riders".
What GS Custom did, was recognize an oppourtunity to launch very long projectile (6+ caliber) from an LGT barrel by employing a slight, but very significant, change to the abandoned concept. By altering the band spacing/width, perfect axial projectile/bore alignment could be obtained with extremely low friction.
In brief, a single band within an array of four or more, is utilized to provide a gas seal while the remaining bands side-swage as the twist angle becomes more acute. It is this deformation feature that continually re-establishes alignment during bore transit.
Gerard also played with more experimental nose/tail projectile geometry in an effort to improve aerodynamics which, as in rifling geometry, is facilitated by use of CNC. Zethilius Associates has simply taken these ideas to the level of refinement possible through use of mathematical formulas used in aerospace. The one exception to this is the tail, which does not have a direct homologue in aircraft, or rocket design. Projectile spin-stabilization is strongly influenced by tail geometry, and it is here that the greatest advancements have been made in the last year.
Can you explain a little more clearly how the TiO2/SiO2 is loaded into the casing and applied to the barrel? Is it mixed with powder? Is a projectile seated into the case and then fired down the bore? If so, how many firings are required? Also, is there some sort of load data for this?
I'm also interested in how all your pieces come together and what hyper velocity perfomance we are talking about and what the price tag is.
I am a big fan of the GS bullet concept and in some recent correspondence with Gerard I've found out that they are proceeding with LRH bullet development. I am looking forward with great anticipation to see what he comes up with. You indicated a tip for your 338 bullet and Gerard doesn't use tips for his hunting bullets. A tip would improve BC, but I beleive Gerard is concerned with reliable expansion. Your thoughts?
Last edited by MontanaRifleman; 06-21-2009 at 09:58 PM.
The means of ceramic dispersion touches upon another of the patentable items. I can descriptively give you some idea of how it works however.
The objective is to have the greatest concentration of TiO2/SiO2 flowing over the area of highest anticipated heat-erosion. It is therefore metered directly into the slipstream of the throat. ATK suggested combining another ceramic material within the propellant itself, and we may still try it, but the concentration becomes much more dilute. The first cartridge "primes" all subsequent firings, and no cleaning maintenance is required.
The explosive propogation velocity is a function of the propellant chemistry. Compare nitrocellulose with either RDX, or HMX, and you will get some idea of the MV gain. This is not really a set-up you would want to take out at deer season, at least not for awhile. Initially it will be limited to military trials.
Components such as the bullet, barrel, and possibly the case, provide more than enough improvement over conventional arms for any conceivable civilian application.
My experience with solid projectile expansion is more an issue of controlling it, not causing it. As mentioned, a frangible bullet is easy, as solids tend to strike with explosive results with simple hollow-point construction. The Ultem tip is one of the means to controlling even expansion (in addition to BC enhancement). Gerard may be using oxygen-free copper. You can get away with a hollow point using this alloy, but it is awfully abrasive to cutting tools.
The only bullets that I have seen by Zethilius Associates looked a lot like those that Lutz Moller had on his web pages in the past.
Those bullets were monometal copper had no ( or extremely small ) hollow point!
Have you come up with a hollow point design? Long range seems to need a bullet of moderately fragile makeup to expand at the lower end of the velocity spectrum.
The recent Lutz bullets seem to have plastic tips, and while that adds to BC I can't believe that they will be as geometrically "perfect" as a CNC machined bullet.